You can probably get away with running your own (there a ton of open source ones, they are extremely simple to write and just a ffmpeg pipe) for your own servers.

I'd imagine these named ones in particular were looked into further because they were straight up collecting monthly fees for content they don't own or have the right to use. And adding ads for their own "premium bots" in every single message the bot sends. And gating features like volume behind $9/m plans.