There are a couple main problems with Linux as a desktop.
1) Is (obviously) hardware support. While one or two vendors will produce a small number of Linux-compatible drivers, they don't do QC testing of all their products on Linux, whereas they almost certainly do for Windows or Mac.
Distros, and OSS devs in general, have to support a wide range of software and hardware in every possible configuration. This includes not only individual components on a system, but how they are tied together, and the proprietary extensions (keyboard buttons) that allow the user to operate them. But there's no way any company could possibly test all software with all hardware. Even if they did such insane amounts of testing, they'd need to pay someone to fix all the bugs that would come out of it. No OSS company I'm aware of has the bankroll of an Apple or Microsoft, to say nothing of all the hardware vendors' investments.
Trying to support OSS on proprietary platforms is like trying to become the development and support for every such product in existence, and those products are often black boxes. The only reliable option is to pick a distro, then find hardware which has been explicitly certified for that distro. This is usually a short list, and becomes shorter as you try to find something that fits your needs and budget.
2) Is an even more intractible problem: limitations of the software.
Do I need some software which is platform-dependent? Then I should use that platform. Trying to shoehorn it into Linux is just a recipe for frustration and support calls to your cousin's son Eddie who you heard is really good with this Linux thing.
Then there's the difficulty of operating a system which is only designed to work in a particular way. Want to use some software which doesn't have an official package? Good luck figuring out how to install it. Have some problem on the system? Good luck figuring out what magical combination of "console commands" might make it work again. And don't even bother telling your ISP or work that you use Linux when you call with a support problem, because they'll just tell you to get bent.
Really, it all comes down to money. Nobody is spending the money on Linux to become an officially supported Desktop, because it would be unaffordable. Linux will always be a hobbyist OS as long as nobody supports it.
1) Is (obviously) hardware support. While one or two vendors will produce a small number of Linux-compatible drivers, they don't do QC testing of all their products on Linux, whereas they almost certainly do for Windows or Mac.
Distros, and OSS devs in general, have to support a wide range of software and hardware in every possible configuration. This includes not only individual components on a system, but how they are tied together, and the proprietary extensions (keyboard buttons) that allow the user to operate them. But there's no way any company could possibly test all software with all hardware. Even if they did such insane amounts of testing, they'd need to pay someone to fix all the bugs that would come out of it. No OSS company I'm aware of has the bankroll of an Apple or Microsoft, to say nothing of all the hardware vendors' investments.
Trying to support OSS on proprietary platforms is like trying to become the development and support for every such product in existence, and those products are often black boxes. The only reliable option is to pick a distro, then find hardware which has been explicitly certified for that distro. This is usually a short list, and becomes shorter as you try to find something that fits your needs and budget.
2) Is an even more intractible problem: limitations of the software.
Do I need some software which is platform-dependent? Then I should use that platform. Trying to shoehorn it into Linux is just a recipe for frustration and support calls to your cousin's son Eddie who you heard is really good with this Linux thing.
Then there's the difficulty of operating a system which is only designed to work in a particular way. Want to use some software which doesn't have an official package? Good luck figuring out how to install it. Have some problem on the system? Good luck figuring out what magical combination of "console commands" might make it work again. And don't even bother telling your ISP or work that you use Linux when you call with a support problem, because they'll just tell you to get bent.
Really, it all comes down to money. Nobody is spending the money on Linux to become an officially supported Desktop, because it would be unaffordable. Linux will always be a hobbyist OS as long as nobody supports it.