If someone gave me a free car and I suddenly discovered that it had stopped working at 8:30am on Monday morning because the free car plan didn't support peak hour, just when I needed it most, I'd be annoyed as hell. This would be the case no matter how much I got paid at my job. Getting a nasty surprise because you didn't realise a product was inferior is upsetting for reasons that should be pretty obvious.

Admittedly the cloudflare free plan does say it's for things "that aren’t business-critical", but what does that actually mean in terms of resource quota and expected uptime?

I don't care as much for DDOS protection as for free easy SSL which gets semi annoying to set up for me personally. I assumed cloudflare was an option from their advertisment and never worried about it. Now I suppose I will.