Kinda depends, I mean sure if you chain kill him it's nice but if he's not like solo hard lane, ganking him involves the usual risks to ganks, on top of ganking a very strong hero(since metamorphosis is basically an ult you can train before 6, if it's up he can and will rape your face if you don't have overwhelming power during the gank). If you don't shut him down enough though, he doesn't need to super farm to carry, he can instead rush a radiance and splitpush you to death. He suffers from the same "issue" as PL and Naga in the sense that once they have radiance, they can push multiple lanes and farm the jungle at the same time, while being in a relatively safe place making them virtually ungankable. Naga more so I'd say because of song.
There's plenty of ways to clear illusions, early on. Once he has radiance and a heart and maybe one more big item, the illusions will be able to kill supports and be annoying to kill even for strong heroes, and that doesn't change the fact they will constantly proxy push the lanes so you have to send someone who can deal with them every minute and a half in every lane he's pushing.
I don't think it's too much of an issue with the hero than it is with illusions based heroes in general and splitpushing with them. It makes for a fairly boring game and is hard to counter especially in pubs. The hero himself could probably use some nerfs though, on metamorphosis or on illusions damage taken/done, whichever. Not like into the ground nerfs, but some stuff. I think reducing radiance damage on illusions would probably be a decent general change though. Doesn't need to be removed but say it does half dmg on illusions, so they don't push as hard nor can they clear jungle camps as easily.
