Search has a discovery problem, though—you have to know what you’re looking for. Even if you know, it’s increasingly difficult to locate it via keyword search. And isn’t Google/YouTube search a type of recommendation engine anyways (i.e. results are conditional on your browsing history and other factors)?

True, though it varies somewhat by dommain. For, say, informational or academic topics, search is at least fair. When researching a specific author or authority, better. For music, not quite so much.

I don't have a YT account, have used it under Incognito for years (keeping session histories minimal and fresh, and as of a few months ago, block all cookies entirely.

This kills some search relevance, but is exceptionally good at avoiding that corner of youtube --- the zone of ever more finely curated crap.

YT's lack of channel-blocking (never, ever, on any circumstances show results from $CHANNEL in search or recommendations, or of creating short-term playlists based on search results, are increasingly crippling. On the latter, mps-youtube has excellent search and list-curation features I use heavily.