The MOBA genre is a bit more lacking in variation than all your other examples... just a bit...
You really meaning to tell me that there's more difference between, say, Starcraft and Star Wars: Empire at War than in Dota 2 and League of Legends?
Having actually played all four of those a fair amount, I'd have to say quite notably so, yes. You're looking at a degree of difference that's closer to that between Age of Empires and Star Wars: Galactic Battlegrounds. Seriously, outside some ease of use/mechanical shifts (that are honestly more minor than not), there's not really a meaningful difference between the two games. They're
considerably more same than different.
The map may be nearly identical, but that's LoL's problem, not the genre's. HoN really shouldn't be considered either because its entire premise is "Dota knock-off".
It really is the genre's at this point. DotA was stuck up the arse of the AoS style in general (Because yes, there were dozens when it came out nearly identical to it, and that never really changed through its entire bloody lifespan), and pretty close to everything that's come after has been pretty explicitly stuck up DotA's. There was more variation in actual AoS-style WC3 custom maps than the commercial stuff, insofar as I've been able to tell.
I mean, cheers to the ones that are actually trying something vaguely different (Which is, like, awesomenauts. S'been all I've really noticed. Starvoid, I think, looked like it was
trying something a little different with a squad mechanic but I can't get it to run so *shrugs*), but pretty much the entire genre to date,
particularly among the ones that have gone some variation of commercial, boil largely down to the exact bloody same two sides/three lanes (sometimes they go to two or four! It's amazing.)/small waves/jungle/almost monomaniacal focus on tactical level strategy/etc. formula. The genre definitely has a problem in regards to design similarity.
I mean, it's enjoyable enough, but the style has fossilized since DotA rose to popularity. Badly.