Kermit as a file transfer protocol, in the more modern implementations at least, supports 4K and 9K blocks, streaming mode (no need for ACKs), sliding windows, etc. As a protocol, it also has an OS-agnostic way to do file management; you can send commands like delete, rename, copy, etc. and the remote end does it in a general way. It's like SFTP, only a few decades earlier.

In modern times, I use it as a powerful ssh wrapper and BBS client. Its character-set translation is ideal for CP437 to UTF8. See https://www.openkermit.org/ckermit/ssh/ and https://www.openkermit.org/ckermit/bbs/

Kermit initially competed with xmodem which was very primitive (but a lot smaller/simpler).

By the time zmodem became popular, the biggest remaining selling point of Kermit was the built-in scripting. Not much use for one-off BBS-style transfers, but very handy for keeping a directory in sync etc.