That's not really true. A lot of self-modifying code follow very predictable patterns where the modifications treats addresses in parts of the code as a variable. In 6502 code in particular this is a common idiom for looping over arrays of more than 256 bytes. Many of these patterns are easily detectable and easy to statically rewrite.
You likely can't handle the general case, but that's a lot less critical. Especially for old consoles or computers where the pool of software with too complex cases that can't easily be handled with generic analysis is small enough that you can reasonably add special cases for most stuff you care about.
You likely can't handle the general case, but that's a lot less critical. Especially for old consoles or computers where the pool of software with too complex cases that can't easily be handled with generic analysis is small enough that you can reasonably add special cases for most stuff you care about.