They're also useful for separating multiple lists when using a comma would make it look like an item is an extended list.

So let's say I want to express:

"My contacts are:

• Jessica, Cook (as in a job title, not a name)

• James, MD (as in the professional certification, not the name 'MD')

• Doug, ABC (maybe to show that Doug works at ABC)"

If I said:

"My contacts are Jessica, Cook, James, MD, Doug, ABC."

There's no clear indication of what is a list member and what is a new list. But this:

"My contacts are Jessica, Cook; James, MD; Doug, ABC."

is a bit clearer. (There are probably better examples but I'm shooting from the hip here lol)