It speaks less of Microsoft and more of the vendors who find no need to change their ways. Yes it really is all held together with spit and tape, but nothing has forced them to change from it.
Which translates into a pretty large part of the small business market that doesn't have any de facto choice.
And WINE et al. aren't a scalable solution because invariably these things depend on odd Windows quirks and/or are generally terrible from a code/standards quality perspective. And there's functionally no way to address that because the historical-Windows-in-fact API is "every odd behavior every release of Windows has had over the years."