The unfortunate reality is that for some websites it is essentially mandatory.
The biggest problem with the internet—which I have never seen an anti-Cloudflare post including this one address—is that DDoS attacks are a legitimate, widespread problem. Cloudflare provides protection against this, and does so for free.
Identify for me any other service which does this for free, or even for cheap. I don’t think anyone besides Cloudflare does. When you research this topic, the response you’ll usually get is “lol why u need ddos protection? maybe you don’t.” And no, I do 
Even if (and that’s a big if) there is a Cloudflare alternative that’s accessible to regular website operators, it would certainly operate in pretty much the same way as Cloudflare on a technical level. And that means you’re still trusting someone to perform this task, and control your network.
And then we’re getting into double standards territory, where you have to answer “why do I trust this alternative service more than Cloudflare?” Usually there isn’t a reason other than that the alternative is smaller, which is hardly a reason to choose a service.
I don’t think it’s great, but it is what it is.
