What I don't understand is the discrepancy between the size of their engineering workforce and the lousy quality of their web client on mobile.
I've been in an enterprise-y work environment. It's amazing the crap that gets churned out by massive teams for simple tasks.
If you switch to "Desktop" mode in a mobile browser. The messenger is so freaking buggy and unusable, it deletes text as you type and try to send a message. It's made to frustrate you so you download the messenger app.
This is why Google has products stagnate for years before it is finally euthanized, allowing a completely new iteration of it to take place.