Earlier quoted context omitted.
How many websites ever get passed the signup stage? I often will leave as soon as I'm tasked with creating an account and I'm not likely to come back.
What is especially frustrating that many sites don’t allow Mailinator and other similar ‘one-time’ email systems to be used for registering an account. No way I am going to give you my email address up front before seeing the product. Now the solution is of course to have a separate gmail account to register. Most sites still allow user+site@gmail.com address syntax so that I can sometimes see who are leaking where.…
Well, there's always this: https://articles.uie.com/three_hund_million_button/ -- trigger warning: that page has annoying delayed-by-few-seconds modal popup that begs you to subscribe and, incidentally, hand out your email address; the irony must have been lost on their marketing folks.
Unless your business is REQUIRED[×] to have user details on file, putting any kind of friction on the user's action path is equal to voluntarily giving up sales. No, I don't want yet another account on your shitty website, no matter what it sells to me. If I end up coming back often enough, then I may, voluntarily, create an account. But if your site requires to create one up front, I'm incentivised to take my business somewhere else.
The worst offenders try to do email domain TLD matching against country of residence. I've seen it only twice, but it's such a user-hostile pattern that it has seared itself to my memory (while mercifully having relieved me of the memory of where I ran into it).
×: cough gambling, financial services, insurance, etc.