It's just an ugly ass syscall extension mechanism (so it has no direct equivalent in Linux lets say), it definitely looks bizarre in modern times.

Int 2F is initially handled by DOS as a stub, but additional programs (like drivers and TSRs) can override INT 2F, put their bucket of functionality and then fallback to whatever the previous installed handler was (called chaining) for whatever they don't handle.

This gives a glimpse into how much various crap could end up installed as an Int 2F handler: https://www.minuszerodegrees.net/websitecopies/Linux.old/doc...

It was often used for feature/presence checks and usually nothing time critical as that chaining setup was most definitely not timing friendly.