Why do some companies ask the users to "Text for a link" to download the app?

I've noticed several websites that ask for a phone number to link to either the Apple Store or Google Play to download their native app. (Example below) and I've also seen a few sites display links to the Apple/Google play stores and ask for a phone number.

This whole concept is confusing to me because:

-How does this make it easier? -Why would a company expect that the user would give up their phone number to get the app? -Do users prefer this to being emailed a link?

I'm just curious because I've seen this in other places and I want to know the reasons behind it or if some executive of a high-profile startup just came up with a way to harvest a bunch of phone numbers. I would love to know if this a useful thing.