I definitely have single point of failure concerns both with Cloudflare and Let's Encrypt, but as another user points out, right now 8.8.8.8 is the much more common single point of failure for DNS, and it's run by an ad/tracking company.

It's definitely possible Cloudflare may go the way of Google at some point in the future, but right now, I'd rather have the former than the latter involved in my Interneting. And in this case, it's a new/additional option, a second point.