.NET actually was known as COM+ for a time before public release. Environment variables for tweaking internal behaviour still retain that moniker.

COM+ was basically Distributed COM, and was available for years before .NET. .NET Framework was implemented built on existing Win32 and COM/COM+ calls though, which is why you might see that.

Distributed COM was known as DCOM, COM+ became known as CLR.

You're both sort of right. There was something that was released under the name COM+, which was a bunch of services on top of DCOM. But what became the .NET CLR was also internally called COM+ (or part of COM+?) under development.

see https://wiki.c2.com/?ComPlus

I think what happened might have been similar to what ended up happening with the .NET name later - there was a name associated with an umbrella strategy, a bunch of different technical components were under development associated with that strategy, but only some of them were released before the strategy changed again, while others were repurposed/repositioned to be part of the new strategy.

This is a common pattern with Microsoft product/feature naming and I think it's one of the reasons everyone including Microsoft developer relations people routinely comment that Microsoft "not good at naming things". It's continuing now with UWP and WinRT, where those names are actually used to refer to a bunch of different things that were once part of a now-defunct Windows strategy - some of these things are now deprecated, while others (like the WinRT core language interop model) are still the basis of most new Windows API development, but this is very confusing to developers because of their association with the abandoned overall UWP strategy

Unfortunely the only thing that didn't die with the strategy was the deep ingrained love for everything COM that the Windows team has, and they keep going at it without realising the rest of the world is done with COM, and we only endure it due to lack of alternatives in Windows APIs.

If they only had kept the way .NET Native and C++/CX exposed COM, but that would be too easy for their ways, and those tools are now gone.

It was the year 2000, web services was the hype of the .com bubble. So Microsoft pushed the web services in the net. Hence, all the products .NET. Windows Server .NET, Visual Studio .NET, .NET Framework etc.

It was marketing.

Ironically that hype is the 2021 reality with SaaS and Web APIs everyhwere.