People believe what they want.
But, you are correct.
Not necessarily because FF is bad, but because the internet and web standards are often stupid and not privacy friendly.
Webrtc? Great! (But, by default, it leaks your real IP address even with a VPN). WebGL, web GPU, etc. Sketchy not privacy friendly standards
But, again. At least FF allows obfuscation either by fingerprint blocking or masking or other config settings. But… it is tedious. And they change flags and flag names constantly.
FF at least allows you to mod it so you can use it without leaks.
What irks me is all the telemetry. And this new deal they call fog.
And the impossible to get rid of add-ons I never asked for. No, I don’t want screenshots built in. Nor amazon, or google, or eBay, or Normandy or opt out studies
After all the tweaks I make manually (arkenfox user.js is nice, too) it ends up well over a hundred settings to get what I want functionality and privacy wise.
And, yet, it is still the absolute best of the browsers.
(Tor, mull, and librefox as well)
Or mull - made by mullvad, the VPN guys. It has all the tor privacy without the tor network and gets updates because, unlike tor, it’s not based on the ESR.