I don't think it's on purpose, just a naïve consequence of using the URL for state.

Pretty common.

I find the back/forward buttons useful for undoing/redoing changes, so that I don't lose past cool designs / settings, though I can see it being a controversial approach.

That said, there were definitely way too much history generated when typing into a text field. I just implemented a planned compromise, where you only get a history event when changing a "committed" text field (meaning you previously defocused the field). Hopefully this is the best of both worlds!

Should be replacing state in the history stack rather than pushing a new state.

Right-click the back button?

Browsers only display the last 10 - 20 states, so if you've been clicking around it quickly fills up with just this page.

Would be nice if browsers would group back button entries by: 1. same url except hash 2. same domain 3. rest

Safari does this

Where’s the right click button on my phone

Long press

Agreed, was very annoying, please don’t misuse history like that :(