I believe the people behind peertube know about that. That is why Peertube is so much on federation with ActivityPub. If done properly this would allow anyone with an account on a website using ActivityPub (like Mastodon) to interact with the author of a Peertube video.

Granted this a both a technical problem (that I believe solvable) and a financing problem. It is hard to compete with the GAFAM and their advertising departments.