Yep, the Italian virtuoso openly admits that string hopping is THE problem (which probably led him to develop his god-like fingerpicking technique instead):
Also, it feels encouraging to realise that even the best players in the world have similar experiences as the average Joe because that means there’s nothing “wrong” with me.
Brett Garsed also has trouble with string hopping, it’s part of why he developed his hybrid picking.
Brett Garsed: string hops, becomes killer legato player.
Matteo: string hops, becomes killer finger picker.
Me: string hops, becomes…mediocre string hopping player 
Yeah, same here. I still have yet to find that one difficulty that’s gonna make me an absolute genius at something else LOL
I watched his whole interview with Beato - your parenthetical isn’t quite right: he always played fingerstyle, it was never because of problems picking. So who knows, if he had sat down with a pick for a while he might have ‘figured it out.’
I guess the point is that It is very rare to see a prodigy being just a human (like Matteo’s two seconds of suboptimal picking during the interview) as opposed to, say, Gambale who developed his whole speed picking thing as if his alternate picking wasn’t already mind-blowing enough.
I don’t think I’ve ever seen footage of Frank play prior to the development of his sweep picking technique. I must have a look for that.