For a while I would get web pushes from some new site I just have visited once and accidentally accepted. I had no clue how to disable them for ages until a friend showed me. (Yes I could have looked it up, never reached critical energy)
I have to imagine many people are in the same boat.
> Notification prompts are very unpopular. On Release, about 99% of notification prompts go unaccepted, with 48% being actively denied by the user.
So 99%+ are spam and the rest are probably users who accidentally hit accept.