I think as far back as ME1's ending it was clear Bioware sort of wrote themselves into a corner. Sovereign literally smashed through at least one cruiser on its way through the Citadel fleet and even the entire Fifth fleet can't take down its shields, but conveniently Sovereign seems to be concentrating on the Saren-corpse fight so that when it is destroyed then its shields finally fall. Adding Thanix cannons to their arsenal might have made the odds more even, but then the ME games are all about Commander Shepard doing everything, almost nothing is accomplished unless Commander Shepard is there to push the button. Yeah, ME3's Destroy ending still really sucks. ME2's "suicide" mission or some of the sidequests are usually preferable in that the "normal" ending still requires sacrifices, but that if you get everything, carry over your ME1/2 saves, found every Matriach writing in ME1, then Dr. Conrad Verner would turn out helpful and your entire ME2 squad could survive ME2, compared to Ashley or Kaidan dying at Virmire, and even in ME3 for a pure paragon or renegade ending requires some squad members' death (Thane at least), yet if you worked hard in ME2 many more survived. Then in the very end, the most... traditional option of blowing up the Reapers also requires wiping out loyal EDI and the potentially helpful geth. The other endings are even more crazy and weird so that already set a low standard. And that's not even going into the whole "break the mass relays permanently" that they edited out in the Extended Cut as no mass relays mean no galactic civilization period. I think the protheans were probably significantly more advanced than the species of Shepard's cycle. Partially its a storytelling requirement, that the Citadel races be somewhat advanced but not too advanced, and that everyone be at about the same tech level, despite many of the races having been in space for centuries (and at least two species literally living that long and beyond), whereas the new Systems Alliance reaches parity pretty fast (well, it entered the galactic stage on mostly peaceful terms, but its not like turian scout ships could survive an Alliance fleet even at first contact). But the protheans were on the verge of building their own personnel sized mass relay (the Conduit at Ilos and its counterpart on the Citadel) and apparently the Citadel races... never bothered (based on something Aethyta, said in ME2)? Which makes the asari look even lazier when they had a working prothean beacon for centuries but never even donated it to the Crucible effort until it was too late. But then a lot of the ME trilogy also involves everyone shooting themselves in the foot while Shepard has to do everything. Apparently just super-powerful enemies aren't enough for a "dramatic" story anymore, the heroes have to sabotage themselves just as much if not more these days. The post-RotJ NJO novel series, SWTOR (partially), Harry Potter, probably plenty others. Before ME3 I had hoped that a concentrated arms build-up would lead to more of a slugfest instead of a slaughter, but then turns out all of ME1 only bought... three years at most? Two years between ME1 and 2, and I think ME3 starts six months after the Arrival DLC? Compared to the protheans changing the keepers on the Citadel which probably bought decades for the next cycle, as then Sovereign had to fight to get to the Citadel, not that it did much. Considering how near unstoppable the Reaper capital ships were, they could probably have taken out more resistance faster, but then they already had earth partially harvested so it probably didn't matter that much to them. Which is probably why they didn't bother with taking the Citadel earlier, before sneak attacks ensured the Reapers would wipe out all the leaders and get all the top info instantly, now even if the Reapers quickly overwhelmed the Citadel fleet (which they probably did), they still wouldn't get the records which would lead to a quicker victory. You'd think they could still use the Citadel to shut down the relay network, but then one also wonders whether control of the mass relays couldn't be used against the Reapers. But then I think a codex entry mentions the Reapers used all the mass relays, including the dormant ones so aside from a quicker victory, the Citadel wasn't that super-important until the Catalyst was discovered. And then one tries not to think too much about how the Catalyst invalidates most of ME1.... I still wish we had seen at least some dreadnaughts successfully taking on Reapers, instead of the same old Reapers blowing up ships (which looks cool, but still). According to the codex, multiple dreadnoughts can take out a Sovereign-class Reaper, but of course the problem is that even if it was 1-1 Reaper vs. dreadnought, they're still seriously outnumbered and every engagement the allied fleet would still lose dreadnoughts far faster then they could replace them. Faster than Reapers could build more of themselves, but still not fast enough. And that's not even going into how bad the ground battles were. ME always had a few plot holes, which got worse by ME2 and were huge problems by ME3 (such as why Sovereign had to bother with using Saren and geth as ground troops when the Collectors were there), as well as how much control they always had over the mass relays. In ME1 according to Vigil sounds like the Reapers won overall almost instantly and then just gradually repurposed every isolated prothean population. Now according to Javik, sounds like the protheans still put up a pretty good fight for decades after the Citadel fell (with the Reapers continuing to come up with new monstrosities), but still lost eventually. But guess the point of a lot of Shepard's appeals/threats for cooperation was that if the species of the galaxy didn't work together now, there would be no chance later... now that it convinces many of them, and even the more willing require a few concessions (the turians want krogan reinforcements on their homeworld, and they're probably the only ones actually sort of holding their own, the krogan want the genophage cured, the quarians want their homeworld back), compared to the asari and salarians. And I'm not even going to bother bringing up how minor the rachni turned out to be.