"Don't roll your own" is perfectly sane advice...

For those not trying to implement the dark patterns that enshittify the web.

If you don't roll your own back button behavior, you've missed the opportunity to show a few more ads.

If you don't make your window full screen on my shitty old tablet browser (yes, I'm looking at you, BBC), then it's far too easy for me to close your window. (Joke's on you, though -- my old Samsung tablet has a physical back button.)