Quote -
If an "IBM compatible" machine did not run a piece of IBM compatible software, the customers came screaming back to the dealer who in turn went crazy to the manufacturer. I know, I've been there up close.

Not close enough, I'm afraid... the computer maker would blame the software author, the software author would blame Windows (and DOS before that), and/or the hardware (you didn't have enough RAM, your CPU isn't fast enough, you're using a Memory Stacker, your version of Windows or DOS was wrong, it's some TSR's** fault, etc). The OS maker would take a complete hands-off approach, and nobody would take responsibility. The only thing you could hope for would be the responsible party (whoever that was) to get a bad reputation and lose business.

By the way: Read a EULA (End User License Agreement) sometime... you'll still find it in there where software makers aren't responsible for anything but (maybe) a defective floppy or CD-ROM, which they would replace free of charge. 

**TSR = "Terminate and Stay Resident", or basically any application that rremained suspended in RAM when not directly called - common way before the age of multitasking and threading.

I've been in that particular biz for far too long, and I very much know better. ;)

Quote - I never said I wanted perfectly matched results - that is what you made up. I said I wanted to have POSER compatible results meaning not looking rubbish in any version of Poser.

Quick - define "not looking rubbish". Bad lighting can make a perfect mesh look like crap. Bad camera angles can destroy a certain facial expression.  Fact is, you cannot place an objective definition on compatibility beyond loading and being free from obvious defects (reversed normal, misaligned texture, etc).

Quote - I do not have these problems with Renderosity, RDNA

You may not, but others certainly have. I pointed out some rather famous examples a few years ago... the thread that did so was deleted outright here, a similar one managed to hang on for awhile at RDNA before getting locked, and the other, longest one may still be archived at the old PoserPros site. Many merchies went predictably ballistic. I received more than a few threats, flames, and other tear/rage-filled missives in reply. I also received a larger number of messages in encouragement, explaining that the problem was (at least back then) rather widespread. 

Funny thing is, I'm willing to wager that there are still examples today, and at all sites - just have to dig deep enough to find them.