TLOU2 isn't truly linear in the way that, for example, a visual novel might be. In TLOU2, the main story beats are consistent from game to game but the actual gameplay experience could vary a lot from playthrough to playthrough. Also, TLOU2 is a rather long game (20-30 hours according to HLTB) so the scenario where someone watches a stream a bit and then decides to buy the game to play the whole thing themselves seems much more likely than it would be with a shorter game where someone might just watch an entire playthrough and have no desire to play it themselves.
Which really is one of the main issues here - there are so many different types of games that's it hard to make a blanket statement that is true for all games.
BTW, we give permission for people to stream any and all of our games.
You have multiple people participating in streamer communities.
From a strict sales perspective(ignoring goodwill benefits for now), in my mind, you have people that watch the stream and would never buy the game no matter what. People who watch the stream and could be motivated to purchase the game. People who watch a stream and are suddenly discouraged to purchase the game but would have purchased the game absent a stream.
First off, group one doesn't matter, at all. They aren't worth considering and aren't worth worrying about(though as I prefaced, you could break that group down further into people that won't play but will spread goodwill, and people that won't, the former being of benefit and worth considering). What seems to be the argument some are attempting to make is that there are more people in category 3 than 2, but all the signals from the people most invested in determining whether that is the reality, publishers and studios, seem to think the opposite.
I can maybe see a scenario where a studio with an entirely linear experience may see a net negative, and so that would be where they could use their legal leverage to impose restrictions, but it seems my sense, which is all we have without concrete and reliable data, is that all the market signals communicate this to be mutually beneficial. With no guarantee that a disruption on a large scale to impose licensing fees would maintain that.