Discord hardly works
Wut? I use Discord in Linux (Nobara) and it works just fine, including activity detection and screen sharing. Sure, Discord on Linux had some limitations in the past, but that's no longer an issue, assuming you're using a decent gaming-optimised distro like Nobara.
Linux would've already passed 5%
Highly unlikely. The low market share is mainly because a) Linux does not come pre-installed on most computers - the vast majority of users just buy prebuilt computers and use whatever OS it came with and don't tinker with their systems and b) most people like to use whatever system they're familiar with and will not change unless they have a very very compelling reason for switching.
In fact the only reason why the marketshare jumped recently is thanks to Steam Deck. If we want Linux numbers to go up, we need more systems like the Steam Deck, and more companies like Valve to work with upstream kernel and other projects to implement much needed features and accelerate development efforts.