That is sadly true. Edge only runs on Windows 10 BUT given that Micorosft freely offered upgrades for Windows 8 machines and data from stats counter, windows 10 usage is more than windows 8.X.
However, according to stats counter, Android is now more popular than Windows.
That leaves us with the elephant in the room for the windows market: 7! That bad boy has roughly 40% of the windows market according to stats counter. But considering that IE only holds 3% of the market, I’m assuming a big chunk of those Windows 7 users are running Chrome or Firefox. So we’re good! :)