Cathedral-style development doesn't necessarily mean closed-source, but instead reflects the less-modular nature of Wayland in relation to x11. There aren't multiple desktops that are all using the same display server; instead each desktop implements it themselves around a common spec. Plug-and-play software has fewer and more restrictive interfaces to rely on. Modern desktop Linux is decidedly pared-back, which is a good thing when you consider how scarily open Linux is in the right hands.

"sole advantage" isn't correct either - there's a plethora of reasons to use Linux. In the enterprise, people pay companies money to keep their Linux away from bazaar-level patches and randomly packaged repos. More casually, a lot of people don't use desktop Linux for a particularly advanced purpose and just treat it like a Mac/Windows/Chrome machine with fewer advertisements. Some people do very much get a lot of value out of the bazaar-side of Linux, but the comparison between the two styles wouldn't exist at all if Linux didn't entertain both philosophies.