Is there a reason why variable expansion is not allowed in git?

I was trying to make my .gitconfig cleaner and easier to maintain, and I found that variable expansion isn't a thing. Why is that?

A use case that this would be useful is having several commands requiring the same parameters which are long and hard to read and maintain, such as a regex. You can see my question on SO here: https://stackoverflow.com/questions/72005402/is-there-a-way-to-define-and-use-a-user-defined-variable-in-the-gitconfig-file

Although an answer was submitted, it is a very roundabout way to do something that should be very simple. There is the %(var) expansion for paths available, so I would think that a similar simple text expansion wouldn't be that difficult. Perhaps by using curly braces rather than parenthesis?

Is there a place where I could request this as a feature?

Cheers,

JAZ