It's a great example of worse is better in action: a technically inferior platform winning out because it's better at one or two things that enable virality, which is the only thing that matters when all the money is looking for high growth.

In this case, it's that webapps require zero effort and time from the user to get started with, and allow developers to get the closest to the "write once, run anywhere" dream than anything else (if you're doing a decent responsive design, you can even get a good experience on both desktops and phones with much less effort and no gatekeeping), so the development effort is a lot lower.

These two attributes make it really hard for a native app to compete on growth terms with a webapp, since it has a higher hurdle for users, higher initial development costs to target the same amount of users, and higher iteration costs to ship (and get users to install) a new version. It doesn't matter that it's hilariously inefficient; as long as it's just below the threshold where the user tears their hair out, they're not going to jump ship.