Maybe in the Hacker News bubble but that's not "a great many Internet users". People either use what is pre-installed, what they are used to or what their techy friend recommended them.
I am curious as I don't relate to this and recommend Firefox to friends and family.
I don't know whether those are bugs in Firefox or if Chrome is doing something funky that causes it to work but not Firefox.
I haven’t tried using Citrix for years. It used to work fine in Firefox, but given the quality of it I wouldn’t be surprised if they’ve broken something.