That is actually something I quite like about Discord. Whatever I write and post, while not "private" is not indexed or searchable by anyone other tgan those people that have been vetted (invited) by the respective community. Not that I'm mostly on small friendgroup Discords with 10 - 100 members.
It's similar in Apple's strategy of trying to get Macintosh into the classrooms (in the 80s/90s), and student discounts on Adobe products.
I am not a huge fan of Discord, although I do use it. It's very good at what it does, and the communities it houses are well moderated, at least the ones that I have joined. I dislike that they've taken over communities and walled them off from the "searchable" internet.