All code is replaceable. It's bad APIs that are hard to get rid of.

Most POSIX APIs, for instance, are confusing, obtuse and unnecessarily imperative but still good enough in spite of being 40 odd years old. There's way too much code that implements or calls them to justify making significant changes as this point.

We are talking years and decades, where "replacing" is applied to entire applications, not chunks of code.

Especially in SOA, it can be cheaper to replace a poorly written service than trying to rewrite all of it over time.

> If it's broken but in familiar, known ways, with runbooks, and the cost of rewriting it is way higher than supporting it for 5 years & hopefully we'll move away from the business model which requires it, don't fix it.