A good reason to wait a few years is precisely so that we have a clearer picture of what strengths and deficiencies a piece of tech brings to the table, especially out in the real world.
We have a good picture of how Angular and React works in production now. We cannot say the same for something like Svelte.
De jure deprecation, correct - but reading between the lines in Facebook's own blog article that introduced Hooks ( https://reactjs.org/docs/hooks-intro.html ), which put a bit too much emphasis on "There are no plans to remove classes from React.", which to me means they're definitely going to be deprecating class-based controls in the future.
We have a good picture of how Angular and React works in production now. We cannot say the same for something like Svelte.