So far I haven't had much concrete reason for my family to switch away from Windows. The updates maybe, needing to pay for a new license and the UI changes are like pulling the chair out from under them, especially as they get older (Windows 7 was hard for my grandma, thankfully they left 10 mostly alone but 11 is quite different again so she's currently staying on 10 — not that her hardware supports 11 anyway but that's fixable), but it's either learning the new Windows UI, let's say ten storypoints of newness, or learning some Linux desktop environment, even if it's Mint which is similar to 7/XP it's not quite the same either and probably like 15 storypoints at minimum, even if then you're done for much longer

But if OSes are being locked down and software has trouble distributing security updates through official repositories for Windows... that's a good reason to finally make the switch. Same as why my family is on Android: I can install f-droid, disable the google store, and don't have to worry about them installing malware / spyware / adware

There's different degrees of openness. Android till 2026 was an acceptable compromise (let's see how it goed forwards). Windows is also on the decline with their account policy, not sure about this certificate revocation thing (thankfully haven't had to deal with it yet; I'm not a user myself) but it sounds like they're moving to a walled garden also

When the degree changes and gets even less open, yeah you can say "well of course, they were never truly open, they're commercial" but it's still a change and might lead people to alter their choices

You'll find that people that are not computer experts will take to modern Linux with much more ease than those that have complex needs, which for 90% of the people these days means that access to the Web satisfies all their needs. Moving from Windows 7 to 11 will probably be as traumatic as moving from Windows 11 to KDE, so it's an investment worth doing in my opinion.