Re: MSX
Well said. There is one very particular thing that would have wound up being the MSX's Achilles' heel had the standard reached the sort of market penetration that Microsoft hoped (comparable to IBM compatibility - remember that this was not just a hardware standard but a software/OS standard designed by Microsoft and ASCII Corp).
The MSX memory map was left relatively free and open in order to accommodate varying amounts of RAM across model lines and allow compatibility between low-end and high-end systems. Many of the very earliest systems had 8k of RAM, which was pretty much useless but it kept costs down, allowed some BASIC programming and let you play cartridge-based games. However since the MSX standard didn't hit the market until 1983, RAM was cheap and these low end systems didn't really appeal to anyone, so dictating a minimum of 32K if not 64K would have allowed them to nail down a standardized memory map.
The result of the memory map is that different regions (and occasionally different companies within the same region) wound up settling on different memory maps. Now, the MSX standard made allowances for this and properly written software generally shouldn't have problems, but by-and-large what really happened was that software makers just assumed that all MSX machines used the same map as the dominant manufacturer in the region. This meant that, unlike MS-DOS software, a significant amount of MSX software just assumed the RAM was at a certain 'Slot' in the internal mapper and then crapped out when it turns out something else was mapped there. At the time this would have been inexplicable from a consumer standpoint and likely resulted in complaints to the software company, who probably would have just dropped the product and any future product intentions.
This gets even more fun when you take into account the other big highlight of the MSX standard, and the reason for the international popularity that wound up highlighting this problem - non-roman character sets. Since one of the main companies involved in the original standard (and the biggest market) was Japanese, they implemented a fairly thorough Kanji input system. However this wasn't quite standardized, so when they made Korean and Arabic MSX systems, things also broke in new and interesting ways thanks to the memory mapping.
My MSX2+ is a Korean one that I imported a few years back when someone found a cache of them in an abandoned school. Great specs for the system, but despite having 128k it has a very odd memory map that means that software is a crap shoot.
There's a more in-depth write-up here: https://www.msx.org/wiki/MSX_compatibility_problems
The MSX still has a massive following in the Spanish retro-computing community and a significant fanbase in the Russian retro community.