Zig heading toward a self-hosting compiler

You could do that anywhere. Go ahead and allocate all the memory you need upfront.

> More complex than typical zOS installation? Which handles OOM just fine?

If it does, it's because it keeps things in nice neat boxes and runs a closed set of IBM hardware, in the way that a desktop OS can't and doesn't. A kindergarten class at recess is more complex in some ways than a thousand military men marching in formation, because you never know when a kindergartner is going to punch another one or make a break for freedom.

> SMP or general complexity had nothing to do with it.

That's silly. If you're writing a game for a Nintendo or a Commodore 64, you know how much memory you have and you will be the only program running. MS-DOS was slightly more complicated, with TSRs, but not a whole lot. Things nowadays are complex; a message box calls into a windowing system and needs fonts loaded into memory and text shapers loaded; your original MacOS didn't handle Arabic or Hindi or anything beyond 8-bit charsets. Modern systems have any number of processes popping up and going away, and even if you're, say, a word processor, that web browser or PDF reader may be as important as you. Memory amounts will vary all over the place and memory usage will vary all over the place, and checking a function telling you how much memory you have left won't tell you anything particularly useful about what's going to be happening sixty seconds from now. What was once a tractable problem of telling how much memory is available is now completely unpredictable.

> Just general Rise of Worse is Better.

To quote that essay: "However, I believe that worse-is-better, even in its strawman form, has better survival characteristics than the-right-thing, and that the New Jersey approach when used for software is a better approach than the MIT approach." The simple fact is you're adding a lot of complexity to your system; there's a reason why so much code is written in memory-managed languages like Python, Go, Java, C# and friends. You're spending a lot of programmer time to solve a problem that rarely comes up and that you can't do much about when it does. (If it might be important, regularly autosave a recovery file; OOM is not the only or even most frequent reason your program or the system as a whole might die.)

> in a world where people just trained to accept the fact that programs may fail randomly for no apparent reason

How, exactly, does issuing a message box saying "ERROR: Computer jargon" going to help that? Because that's all most people are going to read. There is no way you can fix the problem that failing to open a new tab or file because the program is out of memory is going to be considered "failing randomly for no apparent reason" by most people.

I fully believe you could do better, but it's like BeOS; it was a great OS, but when it was made widely available in 1998, between Windows 98 and an OS that didn't run a browser that could deal with the Web as it was in 1998, people went with Windows 98. Worse-is-better in a nutshell.