Another possibility is that companies think it would be easier to monetize apps than web pages.
If you take ads from a typical ad network and put them in a mobile web page, the page probably will look terrible, and a lot of people have ad blockers in their browsers anyway. (Mobile Firefox recommends AdBlock in its home screen.)
A lot of mobile apps, on the other hand, have ads that cannot be removed except by rooting your phone, and even then, many ads slip through. (I use Android with AdAway.)
Also, people are more used to paying $0.99 for apps than they are to paying for web pages.
I doubt very seriously that ad blockers diminish ad revenue significantly. Mobile Firefox is the default browser on which devices? Defaults count for a lot.
I think we're both right: companies probably do believe they'll be better able to monetize an app than a web site, but they're probably wrong, and they probably think that for faddish reasons.
If you take ads from a typical ad network and put them in a mobile web page, the page probably will look terrible, and a lot of people have ad blockers in their browsers anyway. (Mobile Firefox recommends AdBlock in its home screen.)
A lot of mobile apps, on the other hand, have ads that cannot be removed except by rooting your phone, and even then, many ads slip through. (I use Android with AdAway.)
Also, people are more used to paying $0.99 for apps than they are to paying for web pages.