No actual user cares how their messaging application is made. If it's a progressive webapp or a native app, and the actual experience can be the same, then it really doesn't matter.
> AIM, ICQ, IRC, and Yahoo Messenger all used local clients.
A webapp with a service worker is a local client. And a lot of people use Whatsapp Web, or Facebook Messenger's web site. I know I do.
I think users do care. I care that I can't close my browser without missing messages. I dislike that Electron apps use half my RAM.
If by "don't care" you mean "don't care enough to abandon a platform their friends are on" then I guess I agree. But all you've proven is that network effects matter.
> AIM, ICQ, IRC, and Yahoo Messenger all used local clients.
A webapp with a service worker is a local client. And a lot of people use Whatsapp Web, or Facebook Messenger's web site. I know I do.