"Well, a browser is an app for services entirely reliant on off-phone data :-) Just a generic one"

Which is what I was trying to say though I did it poorly I guess. :-) Why do I need an app when the website will do just fine?

"slower, more battery hungry, with less platform conveniences and access to native APIs"

I think the efficiency loss is traded for the lack of always on services and privacy invasion common in native apps these days.

The important function of the web browser is the sandbox effect.