Coincidentally, I just read an article about the impact large players can have on a financial market when they create a new ETF. The article went into some detail about the various ways the market can be manipulated, and also the unintentional influences the mere presence of a new, huge, monolithic owner of a large share of a commodity can have. It’s rarely a positive event for the smaller players.
There are similarities between financial markets and social media spaces, and social media should take heed from the lessons offered by the much older financial space. Unlike financial markets, the ActivityPub sphere has controls small players can exercise to counter movements like Threads. How effective they are remains to be seen, but I think you’re absolutely right: the existing AP players would be better served by locking out Meta, than to allow the wolf into the playground.