Yeah, I wrote several published games entirely in assembly back when that was really the only reasonable option.
Of course some of the things we had to deal with meant that even the compilers were good, they couldn't have been good enough.
Extreme limited memory is the obvious one, but pages that need to be swapped out at runtime is the other one. An example: The Game Boy had 64k of memory addressing, but would ship with 128k and larger cartridges. 32k of the memory space was reserved for video memory, RAM, and hardware registers (if I remember correctly). The first 16k of memory was always mapped to the first 16k of ROM, but the second 16k of memory was mapped to arbitrary 16k blocks of ROM. 16k wasn't enough space to hold your entire game, so some code would leak into other pages (hopefully not more than ONE other page), but you also had to be able to swap other ROM pages into that second 16k memory region to, e.g., load graphics and game data.
There isn't a compiler around even today that can juggle all of that automatically. At a minimum you'd need to be marking different functions as belonging to different memory regions, but you'd still have to manually keep track of which function was where and ensure you don't try to call a region-2 function from a region-1 function when region-2 is some arbitrary ROM page instead of the extra code page. But often something in region-2 needs to call region-1 to load graphics into sprite registers and then restore region-2 so that the stack frame becomes valid again. :)
And 32k is SUCH a small amount of memory that being able to chip away at every single function was important. You have a function that does two things, but sometimes you just need to do the second? Put a label halfway through and call directly into the middle. You can save a byte here by loading one register into another, because you know that the registers will have the right values? Or you can save another byte there because you've realized that a particular constant is loaded a lot, and you can store that constant into one of the 128 cheap-memory locations? Do it! We need every byte...
Yes it would be possible to write such a compiler, but the level of effort to customize it to the specific architecture would be extreme. Easier to just make programmers do the hard work.
