And for years, it was our most requested feature, by far. We had instructions for how to pin the site to your home screen, and would explain to users how the website does everything an app can do. Still, constant requests for an app. Finally we relented and released one, and very quickly around half our mobile traffic moved to the app without us really trying to nudge people at all.
People just really like apps! I think it suits our mental model of different tools for different uses. We've also found that app users are much more engaged than website users, but of course much of that will be selection bias. Still, I can see how having your app on someone's home screen could provide a significant boost to retention, compared to a website they're liable to forget. For us now, that's the main benefit we see. Certainly don't use any additional data, though I won't argue that other companies don't.
Then there’s a measurement element where app installs became an important KPI around the time ad blocking became more popular and interfered with detailed website engagement tracking, creating a self-fulfilling kind of thing.
On top of this I think another factor is that many websites are in terrible shape, super bloated by ten thousand tracking pixels and third party snippets added willy nilly by marketing teams using Tag Manager, so apps benefit from gatekeeping that bloat to a degree.