I do think long-time stealth has a place in this game, however...
... maybe not on a hypercarry. 
He has always been a weird champion tbh, for one totally binary (a god when ahead, absolutely miserable when behind) extremly so even for marksmen standards. Either ban worthy or never-picked. Twitch when he is strong just melts teamfights, and there ain't much you can do about it, besides praying that he is either stupid, or hoping that your tank and assassin playing teammates are just so on edge that they all jump on him literally the second he pops up.
Generally hypercarries are in a weird spot. Other than self-reliant kiter-adcs such as Vayne they often have superior, if not even obscene damage, but also they are pure glass cannons. Just take Kog'Maw as the perfect example: he needs an entire team protecting his squishy void-butt to work, but WHEN he work, oh well, then that's gonna be a hard game for the enemy.
Obviously, there is a logical counter-strategy to such hypercarries which plays into the intended weakness: always pick them out or engage always hard on them every single tf. That's kinda what we have assassins for.
And here's the problem with Twitch: There won't be a teamfight unless he's already in the perfect position to melt your team, but given that he's invisible you can't just pick him off. So the moment Twitch makes himself actually vulnerable (as vulnerable as you can get with that ult steroid), he has already won the fight (or at least he's certain that he will melt at least one before anyone can even react). And to be honest, that's just frustrating to deal with, and that's not even accounting for the entire team that backs up the Twitch.
An important intended weakness for hypercarries is getting cancelled out through the stealth, resulting in the stuff I see regulary in my games: "OH HELLO!" And suddenly the entire team is close to death, without us being able to do much about it. Oh and before anyone mentions vision wards... let's just say I reached a level where people tend to get literally triggered by them. The moment they see it they destroy it, and they also ward... combine that with the popularity of Duskblade that tells you when you are spotted, and suddenly you can say goodbye to the wards you have placed on the flanking routes.
To be honest Twitch either needs a shift from damage to utility somehow, or to lose the stealth - but as that is kinda his iconic thing, maybe utility is the best way to go. Having both stealth AND the ability to melt an entire team is kinda overkill...
