It's relevant in terms of pfs. Say, you happen to have ciphertext of all traffic to a domain for the past three years (whitepower.forum.example.ru), and you get an urgent need to read that ciphertext. Now, if you could get physical access to any one cloudflare server, and perhaps dump the ram, or do a cold boot attack - that might have been enough to read all that data. Assume for the sake of argument, that the servers hosting the site is (physically) out of reach.
Yes, I wasn't trying to say rotation is useless - just highlight that n servers still lead to n avenues of getting at traffic for all n servers, and that cloudflare did something to deal with the pfs issue. It's worse than n servers without session resumption, but better than it could be.
