hardware + application support

• it provides access to the hardware you have
• it runs the software you need

You fastened onto the first, there are plenty of people who claim to have a "better" operating system that doesn't work as well as Linux systems do with the hardware people have (often, with any hardware at all).

But the second is just as important. When Linux was new the various compatibility layers were vital. Everything from the ABI compatibility that later angered SCO through to projects like WINE helped make Linux a good choice for people who, like most of us, don't write everything from scratch.

Any project that thinks it's going to "be the next Linux" needs to handle both these problems well, as well as doing something _better_ than Linux.