Pretty sure it's Linux not being the default option
Doesn't explain why Chrome beat IE. Or why MacOS has higher market share on the desktop than Linux.
Wine and Proton should have levelled the playing field. But they haven't. Also, if you've only just started using Linux, I recommend you wait a few years before forming an opinion.
It is not a popularity issue. If it were, company after company would have switched as soon as they could make it work (office365, outlook online, whatever SAAS they use, none care about their desktop, only the browser, and all major browsers are available on Linux).
From there, popularity outside the organization is irrelevant, internal support and userbase is for and on some version of Linux.
As this would spread, we would eventually see global usage increase and global popularity become a non-issue.