You don't have to update, it's just that developers seem to like to run the latest stuff, and many appear to build production binaries on their laptops (rather than in a controlled build environment, where dependencies are tightly managed, and you could deliberately stick to an older distribution easily enough).
The dependency errors indicate real issues because of the way most distributions handle backwards compatibility: you have to build on the oldest version you want to support. Those errors happen if this rule is violated. For glibc-based systems, the effect is amplified because package managers have become quite good at modeling glibc run-time requirements in the package-level dependencies, and mismatches result in install-time dependency errors. Admittedly, I'm biased, but I strongly suspect that if we magically waved away the glibc dependency issues, most applications still wouldn't work because they depend on other distribution components, something that's just not visible today.
The dependency errors indicate real issues because of the way most distributions handle backwards compatibility: you have to build on the oldest version you want to support. Those errors happen if this rule is violated. For glibc-based systems, the effect is amplified because package managers have become quite good at modeling glibc run-time requirements in the package-level dependencies, and mismatches result in install-time dependency errors. Admittedly, I'm biased, but I strongly suspect that if we magically waved away the glibc dependency issues, most applications still wouldn't work because they depend on other distribution components, something that's just not visible today.