Looking at the changes in #15230, the fact that = produces valid code (as argued in #15115) seems to be a point against using it. Many sentences appear to use constructs like:

Use :rc:`something` to do something.

or

You can do something by setting :rc:`something`.

These will become:

Use rcParams[something] = "default" to do something.

or

You can do something by setting rcParams[something] = "default".

This implies that you should set the rcParam to its default value, but those sentence often just mean set it to anything.

Originally posted by @QuLogic in #15115 (comment)