[JulianMorrison]

The answer is that before the existence of those companies to rely upon, people didn't rely upon them, they just accepted the lag, or they hand hacked the same globally distributed approach on their own, and it sucked for them, and it wasn't too great for users either. CDNs are big because that's what their function is, to reach the world and absorb traffic spikes, and take the complicated business of distribution of edge servers out of the hands of the people who just want to run a website.

The trade off here is intrinsic and accepting the risks of big CDNs is the right answer.

[mathattack]

Exactly. The question isn’t “a few CDNs” vs “Many CDNs”. There are too many economies of scale. It’s really CDN vs Not? (Roll your own just isn’t feasible except for a half dozen of the largest tech firms)

[TheDudeMan]

Well, you could use two CDNs instead of just one. But that costs money.