Yes, you are right, a Google result for looking up "textual raw state" has "not a single result", ...
but there are about "108.000.000 results (1,57 seconds)", at least just a few seconds ago.
Nevertheless Mp3tag today has not a built in user interface to edit a MTA file as raw text.
If you have a closer look into MTA files, then you can find out something more different to INI files, because Mp3tag stores some special characters in a special format.
DD.20160606.1005.CEST