I don't think it's a question of fears as much as it is the pain in the ass. I can't tell you how many times I've registered to a website to use it just once for one single feature, but I assure you it's many. But yeah, I also don't want associated with them, I don't want accounts, and I don't want to put a superfluity of my information in someone else's hands. So these sorts of sites are quite nice.

> Are people really that scared shitless about their email address that they don't even want a site to have the option of signup/login?

When data theft / leaks are an inevitably, yes. T-mobile alone has gotten their customer data hacked 5 or 6 times.

At least IMO, the neat thing about these isn't a privacy thing, it's that when you don't have an identity associated with the usage of your service, you have to answer some interesting questions (data persistence? Rate limiting? Cost, or is it low enough that it can just be free for everyone anonymously? Etc) which make the solutions fun to check out

I envy how little spam you must receive!