Programming assembly on the TI-99/4A was very educational. And like the poster above, I found Intel's assembly language limited, confusing, and missing so many commands. Plus, the assembly language used software registers so you would get a new set of registers each time you changed your frame location. Intel's hardware registers were much faster, but you spent so much time moving things into the registers, operating on them, then moving them back to memory that the RAM-based registers seemed just as fast. You could multiply two numbers together in RAM without worrying about the registers. Plus, the TI-99 was a 16-bit machine which gave some advantages with larger numbers. You could multiply large numbers without converting everything into BCD (binary coded decimal) first.
It has been almost 30 years since I programmed assembly on the TI-99 but I remember it was much easier than learning and coding around the limitations of the x86 assembly.