Comment by afavour

I assure you Android is capable of the exact same thing.

A lot of apps use webviews to render HTML, often in ways where you wouldn't even notice it's web content. Apps shouldn't use webviews to render external web sites but nothing in the APIs restrict them from doing so (recent versions of iOS have made it seem like they're heading in that direction but nothing concrete).

Easiest thing would be for Apple and Google to enforce this via denying app approvals. Would be a very interesting fight against apps this popular, though.