User blog comment:Ironreaper/Retcons and Contradictions in the Reapers/@comment-3097746-20120419032849/@comment-4950455-20120419053039

I actually thought we saw a Destroyer go up during the big final space battle, but looking on youtube suggests they never even show up in space, at least from what I can see. Still, that Shepard is able to kill one with a simple heavy weapon suggests that the Normandy could probably take one.

As for your suggestion on why they're standardized, the problem with that is that the Destroyers are as intelligent in their own right as the big Sovereign-class Reapers - I'm not sure there's any reason to think they'd be "standardized". It would make sense for the non-sapient Reaper variants mentioned in the Codex, but I don't think we ever see any of those in the game.