Progressive Web apps are an important feature of a browser that Firefox is the only one missing.
For some, it can be the reason to switch to another browser.
In other cases like for the Steamdeck, it's what imposed the choice to only include Chrome in the SteamOS interface.
Other problem even for avid Firefox users, since I wanted Social apps on my pc I had to get them on the Microsoft Store which is an Edge PWA that opens every link in an Edge window, making me use this... other browser.