I think the point is that they have it so locked down you can’t leverage that in a PWA even for the action it is intended for, e.g. to go back from Topic to Topic List. And that is NOT good. You then need an actual button, which is rubbish, given all you are trying to do is repeat the same action as the website has which would seem to be a perfectly reasonable expectation and a de facto standard. It works even in e.g. Whatsapp.
https://meta.discourse.org/t/progressive-web-application-pwa/79217/26?u=merefield