[ClemFandango]

I'm not sure if this could be considered a niche audience, but I install Adobe Reader by default on user machines, mainly because the built in readers with Chrome or Edge don't handle printing natively very well, due to not using the system's print settings immediately. You can bypass it with a shortcut and make changes, but it's not so great when users will select print and click ok, it's difficult to educate them against that. It's much easier to use Acrobat Reader and set it to open by default in that. So this may be the install base, SMB and schools, some large enterprise as well.

Whether that preference will get changed back to edge in a feature update is another story.