5% is honestly meeting that benchmark imo. One in twenty? That's firmly a competitor. Certainly nowhere close to leader but no longer a rounding error you can't even see in a pie chart.
WSL does count. The average Linux user doesn't know squat about how the kernel, drivers, or services work; they just like the CLI. If MS can give them enough of the Linux CLI and functioning packages to do their job, it's game over.
Can confirm. I've been working with a VMWare Linux Mint machine for two years, and very recently installed Windows 11, and decided to try WSL2. It's seamless, and literally Linux. I installed asdf and all the stuff I would normally do with zero headaches. No more vms for me.