Websites that make you create an account just to see basic information
I cannot stand when I click on a website because I want one incredibly simple piece of information, like a price, opening hours, shipping cost, availability, whatever, and five seconds later I'm staring at "Create your free account to continue."
Continue WHAT? I haven't done anything yet.
I don't want a profile. I don't want to choose a password. I definitely don't want to verify my email and then get six marketing emails next week because I was curious how much one stupid thing costs.
The worst ones let you browse just long enough to think the information is available, then blur the exact part you came for. Or you fill out half a form and only at the very end they reveal that you need an account to see the result.
At that point I usually just close the tab and find another site, even if making the account would've taken less time. It's the principle of it.
Why does checking a restaurant menu, getting a rough quote or seeing whether something is in stock require me to begin a long-term digital relationship with your company?
If an account actually does something useful, fine. Save my orders, remember settings, track something, whatever. But forcing registration before you've given me any reason to come back feels completely backwards.
Let me see the information first. If your site is useful enough, maybe I'll want an account later.
Making me invent password number 47 just to learn that you're closed on Sundays is not building customer loyalty.