Efficient in terms of what, exactly?
There are multiple dimensions to this problem. Putting everything behind Cloudflare might give you better uptime, reliability, performance, etc. but it also has the effect of centralizing power into the hands of a single entity. Instead of twisting the arms of ten different CXOs, your local politician now only needs to twist the arm of a single CXO to knock your entire business off the internet.
I live in India, where the government has always been hostile to the ideals of freedom of speech and expression. Complete internet blackouts are common in several states, and major ISPs block websites without due process or an appeals mechanism. Nobody is safe from this, not even Github[1]. In countries like India, decentralization is a preventative measure.
[1] https://en.wikipedia.org/wiki/Censorship_of_GitHub#India
And I'm not even going to talk about abuse of monopoly power and all that. What happens when Cloudflare has their Apple moment? When they jack up their prices 10x, or refuse to serve customers that might use their CDNs to serve "inappropriate" content? When the definition of "inappropriate" is left fuzzy, so that it applies to everything from CSAM to political commentary?
No thanks.