That is precisely my point. We're still doing it and we will be doing it for the foreseeable.
For example:
> It doesn't mean DirectX 6.1 is a great 3D game platform [...]
If your opinion is DX6.1 didn't work, I think what you really mean is "isn't the best option under ideal circumstances today." I would agree with that assessment for mono, but "cross-platform" is not something anyone puts next to "ideal circumstances" when it comes to the work involved in making it happen.
> It feels like we're debating whether the Mono bullshit was waist deep or merely knee deep.
There is certainly bullshit to contend with in mono, but there's bullshit in Microsoft's too. And every other platform throughout the ages as you helpfully illustrated. A topical example is porting a game in C++ vs. writing working code for mono. C++ is uncontested as a working technology, but I would pick Unity on mono in a heartbeat for that task. So where is the line, really? In development all you can do is keep above it and all the better if you can keep your socks dry.
I get the impression you are very unimpressed with mono's failings and have written it off and want to complain about it. That's fine but it doesn't mean the hyperbole you've chosen to express yourself is accurate.