It's O(log n), it has fuzzy search (e.g. noun/verb forms the same word), and you can add qualifiers like `from:Author#1234`.
I can normally join a Discord server for a project, search for a keyword, find someone else with the same question, and read the chat log from that point in time.
Not to say that Discord isnt deeply flawed in many respects, like client weight/resource usage, abysmal search (in server but especially DMs, coarse and clunky permissions systems, audit situation? and the very fact that using animated emojis will cost you 5 dollars per month is just stealing sweets from children, and their absolutely sickening boost (ponzi?) scheme...
No, the reason for that is more likely that all the darn generation-Z kids are deathly afraid (and therefore pretend to be deeply contemptuous) of any old-fashioned technology created by Unix greybeards.
(Now geroffmylawn.)