Return to Zork required 19,519 *KB* of RAM for its sound drivers?! No wonder I had so much trouble getting that game running!
In all seriousness, yes, 580-some KB was an incredibly daunting requirement back in the day. I remember. Oh god, do I remember. I was there for "the hell that was MS-DOS+ISA", and I can vouch for everything you say. I don't know about you, but as I recall it, the ritual was generally "Get new game -> Attempt to install, configure, and run said new game -> Spend sixteen straight hours trying to divine meaning from inscrutable error messages, diving into the murky depths of the system, modifying one setting in one config file at a time until all 3,280,476 permutations have been exhausted, praying to various deities and promising them a religious conversion in exchange for their intervention, etc. -> Fail miserably anyway -> Pick up the phone (which, if lucky, MAY have been cordless, lol) and start calling everyone in the literal, physical address book on the desk who might have more expertise and beg them for their advice -> ??? -> Profit!", or something along those lines. Anyway, I was just confused by your comment because I thought you meant to say that PCem's memory map is categorically unlike that of
any real PC. Now I see that you just meant to point out that the memory maps of any two "real PCs" from that era wouldn't even match
each other, so of course no one should expect PCem's memory map to perfectly match that of any one given real PC. If that is in fact what you meant, then of course I agree.
I'll spare you the litany of RtZ quotes that I sorely want to use to close out this post...