There are countless companies and groups (but only a handful that serve the vast majority of users) releasing a version of Linux bundled with a GNU userland and other open source niceties, all designed to work together as a system. These are colloquially called "Linux distributions".
Linux distros universally use the Mozilla root store. So if a CA told Mozilla "to go pound sand" as suggested by likeabatterycar, the CA would end up distrusted not only by the "2.5%" of browser users, but by every Linux server.
Wait, is it a "conspiracy theory" or is it true? Are you claiming both? I'm aware that Google, Apple, Microsoft etc. could already MITM traffic to Chrome/Safari/Edge browsers if they were so determined.
There are countless companies and groups (but only a handful that serve the vast majority of users) releasing a version of Linux bundled with a GNU userland and other open source niceties, all designed to work together as a system. These are colloquially called "Linux distributions".