There is a weird moment toward the end of the 1990s when Microsoft is trying to show their NT is a serious competitor in this space.

Traditionally this was a profitable niche, Microsoft would like to take a fat piece of that, and instead what happened is that Linux destroyed the profit margin. A million dollars overhead that would have kept a hungry UNIX® vendor alive on your project didn't turn into an extra million dollars on Microsoft's balance sheet, instead it evaporated because Linux is "free". And so then Microsoft lost interest.

WindowsNT was the other operating system of that time.