There's some point where kill speed matters, too.

I mean, sure you could get the 65.5k cap on the stuff in Inner Ra'kaznar, but they surely take a lot more effort than Gates mobs.

If you can kill weaker stuff faster, you might get better XP/hr, kinda like the old days where killing VT was better than IT++. 100xp per 2 min is better than 200xp per 5 min, etc.