It's more that old scans make some people seem stronger or weaker than they actually are. Thor beat Magneto in the 60s which could be considered a great feat... But Magneto was nowhere near as strong as now. In Mags' 1st appearance Cyclops managed to puncture his shield. That Strange scan was soooooooo old. Well, actually Mags has been heavily depowered. But, yeah, old scans can be very deceiving.