If hair regarding low-memory conditions, Internet Explorer and other things all appears in the same function, some abstractions are definitely missing.
Also, if the reason for these things isn't clear, that's what comments are for.
Rewriting code, from my experience, has had only great results.
They didn't have the luxury of having an API that might be a few thousand KB big loaded into memory to act as a single redirection to your underlying implementation. They worked in the confines of bytes of memory, not gigabytes.
We can afford to be generic, to make extensible runtime programmable interfaces and runtime evaluation type dynamism, because we have the performance necessary. But our core APIs are still written like its 1980.
I'd like to think that Linux will continue to run on machines with at most 4mb of RAM with not much processing capacity because if history keeps repeating itself we're going to keep on inventing new devices with those constraints.
Exactly what level of abstraction is good for the "core APIs"? Something actually has to send a series of bytes to be written to the disk, even if a bunch of serialization and encoding abstractions are written on top of that. If the latter is the "core", what's the less abstract stuff that inside that?
A) autoconf is not similar at all to an API layer hiding hairiness in its domain
B) autoconf becoming terrible does not mean that portability abstractions are necessarily terrible