There are good uses for app-specific back buttons, for sure! Two cases I’ve seen - one is a site with “single page app”ish flow for reading sequential posts, w

There are good uses for app-specific back buttons, for sure! Two cases I’ve seen - one is a site with “single page app”ish flow for reading sequential posts, where rather than reloading the entire site it fetches just the JSON data for next and previous posts and updates the HTML; the back button here uses the already-fetched data rather than getting the whole site again. The other case used custom back logic on their site’s back button on form pages to avoid “re-sending form” pop-ups and to avoid losing entered form data. When I said “mildly detrimental” I was thinking of a specific example (go back to the previous page that is on the same domain, implemented solely to improve metrics), so perhaps I shouldn’t have said “usually”.