Because I expect my browser to work for me instead of having memorize workarounds for the new web annoyance of the day.
Clicking "back", noticing that the site broke it, moving the mouse and long-pressing "back" (I normally navigate with a mouse thumb button or a trackpad gesture) is much more annoying than my browser just preventing this from happening in the first place.
Why the Earth should the user not want to implement a fix/workaround/whatever for a problem they didn't cause themselves but can trivially solve?
Because I expect my browser to work for me instead of having memorize workarounds for the new web annoyance of the day.
Clicking "back", noticing that the site broke it, moving the mouse and long-pressing "back" (I normally navigate with a mouse thumb button or a trackpad gesture) is much more annoying than my browser just preventing this from happening in the first place.