At this point I'm seeing an accelerationist angle where having only walled gardens, disfunctional search engines (both in-app and Google) and broken apps and APIs everywhere might force people to think about those things a little.
I'm curious as to what you mean by unsearchable. I have yet to not find what I look for when I go to the search bar. The amount of ways to filter things is generally-enough for me to find what I'm looking for in the first page or two of results.
Not indexed by search engines. I don't use discord(I'm unable to make one because of their ridiculously broken sign up flow), and I don't have an account on reddit, but I still find relevant stuff on reddit all the time through google. And reddit is super useful to me for that, specifically.
I really, really don't hope much of reddit moves to discord, it would be a disaster for the usability of search engines.