The year of the linux desktop will be the year of vendor's linux drivers. This requires the year of stable kernel APIs.

Example: AMD released the drivers of their RX 68000 graphic cards the same day that the card was available. Except it didn't work, at least on Ubuntu 20.04LTS. The reason? A patch between 5.4.0-54 and 5.4.0-66 kernel touched an API! We are not talking about major releases (say, 5.x and 6.x), we are a talking about a dot-dot-dot patch!

(PS: the trick was to downgrade to 5.4.0-54 version, or build the 5.11 kernel from source)

AMD was taking heat for this (at least by some youtubers). Do you think that other hardware vendors are willing to have the same fate? To work hard to create a driver just so that a patch release broke it? Do you think that average joe is going to stick with linux when windows supports its hardware perfectly?

Beside the annoyances already mentioned in the other comments (GUI etc etc), the video autoplay "feature" is enough to choose another browser.

Not only embedded videos start themselves, but when scrolling down the page, the videos push themselves back up! No escape! Sure, we can try and disable this using the about:config, but then some video never work any more.

Mozilla, why do you hate Firefox's users so much?