Windows 10 warns when launching the Firefox installer, suggests using MS Edge instead:<p>https://support.mozilla.org/en-US/kb/windows-10-warns-me-use-microsoft-verified-app
This is a violation of implied fitness. You want your OS to respond predictably and without unforeseen differences.<p>This demonstrates that the OS is operating on behalf of MS and not the user. The OS performs as MS dictates. This is a violation of trust.
Sure it's legal, it's a side effect of "S Mode", their absolutely infuriating safety protocol that locks down just about every useful feature of Windows. A lot of manufacturers enable it during initial installation prior to sale. You have the option to turn it off and things run normally.