X is pretty small.

Elon Musk bought Twitter for something like $41b, and now it's worth maybe half that. Cloudflare alone is worth almost double the pre-Musk market cap of Twitter. Spotify is a relatively small player in the "Internet Content and Information" space, dominated by companies like Google and Meta, but it's still worth more than triple the pre-Musk market cap, at more than $120b. Current X is about the size of Zillow, currently valued at about $16b.

As a small company that is focused on spreading propaganda and hate speech, building a robust CDN isn't a core part of X's business, so it's normal they'd outsource that. Companies like Meta and Google are big enough to justify doing that in-house.