First Class SOLDIER vs. SeeD

[champagne supernova]

And these First Class SOLDIERs aren't particularly difficult to defeat. There are some SOLDIERs that are very powerful, such as Sephiroth & Zack, but these are rarities.
This works both ways. In VIII, Squall, Zell, Quistis etc. are exceptional SeeDs.

SOLDIER First Class is a very exclusive group. (Yes, you can run around in circles and fight hundreds of them if you want, but that's a gameplay conceit.) And the reason they're possible to defeat is that you can't fight them until the game is nearly over, at which point your party has built themselves up to be comparable to the likes of Zack.

Over-rating them a bit. It's not like they're particularly tough to defeat. But if they're exclusive, then SeeD should have a serious numeric advantage.