Clickbaity title on the original article, but I think this is the most important point to consider from it:
After getting to 1% in approximately 2011, it took about a decade to double that to 2%. The jump from 2% to 3% took just over two years, and 3% to 4% took less than a year.
Get the picture? The Linux desktop is growing, and it’s growing fast.
Some sites provide a different behaviour depending on the reported OS
I thought this may be a consideration too, but I would expect it to be a minority of websites that would do this, no?