In my experience this all boils to the fact that usually it's not the actual chosen technology stack but the missing craftmanship when making the stuff first time.
Then you either end up refactoring the whole setup for years (which usually is expensive, slows down the business development velocity) or rewriting it from scratch (or as a new implementation next to the old one).
If the original implementation would've been sanely made. Then making new features on top of it (or partial replacements or micro-services etc) wouldn't be that big issue. But usually these beasts are more like godzilla-level monoliths with bad architecture etc so it's probably easier to rewrite the whole thing.
Then you either end up refactoring the whole setup for years (which usually is expensive, slows down the business development velocity) or rewriting it from scratch (or as a new implementation next to the old one).
If the original implementation would've been sanely made. Then making new features on top of it (or partial replacements or micro-services etc) wouldn't be that big issue. But usually these beasts are more like godzilla-level monoliths with bad architecture etc so it's probably easier to rewrite the whole thing.