Its the same kind of people that claim Linux is too unstable for them, and when you ask when they tried it they say 15 years ago.
I've been using Linux on my desktop for ten years and I definitely experience bugs and performance issues with Firefox from time to time that don't occur in Chrome. It's rare but common enough to keep Chrome around as a fallback.
A few: Developer tools are quite slow; Airline websites often break during checkout; JS games and video players sometimes stutter or use a lot of CPU
My favorite anecdote on this front: someone posted a comment on Lemmy, a fediverse alternative to Reddit, claiming Arch was "broken" and Linux users were delusional for thinking it was functional for the average person.
And when people ask them what they meant, they revealed that they used some package from the arch user repository that apparently required manual compiling for every update.
And instead of thinking that this wasn't the unusual behavior of a particular package, they insisted that this was the normal Linux packaging experience, which was why Linux as a whole was a terrible operating system.
A bunch of commenters chimed in emphasizing that the whole package distribution system in Linux is designed to among other things, handle dependencies and avoid manual compiling (though it's available as an option), and they were all dismissed as just being fanboy apologists.
I last tried Ubuntu as a daily driver in 2009. How has Linux reliability improved for consumers since then?