But the nature of a CDN and most other products CF offers, is central by nature.

If you switch from CF to the next CF competitor, you've not improved this dependency.

The alternative here, is complex or even non-existing. Complex would be some system that allows you to hotswap a CDN, or to have fallback DDOS protection services, or to build you own in-house. Which, IMO, is the worst to do if your business is elsewhere. If you sell, say, petfood online, the dependency-risk that comes with a vendor like CF, quite certainly is less than the investment needed- and risk associted with- building a DDOS protection or CDN on your own; all investment that's not directed to selling more pet-food or get higher margins at doing so.