It’s at least partly a holdover from the GSM/2G days, and it serves almost no purpose for end users because every carrier just uses it to try and sell you things you don’t want.

It is possible to disable the SIM Toolkit app if you know how to use ADB, at least on some devices. There’s a few guides around for it.

It’s worth noting that disabling it doesn’t really cause issues in most cases, since the actual chip functionality is handled by other programs.

Edit: Looks like the link I sent got redacted somehow, but either way searching for stuff like “adb disable sim toolkit” seems to give you answers.