if you standardise one thing, what is it and why

Music teaching, we should use the Kodály method everywhere (where it's applicable)

But if only one thing, the hand signs (solmization) should be standardised by how Kodaly imagined it; a relative solmization system with all the 12 notes.

I just can't understand why everyone is focused on the absolute naming in music, absolute distances etc. when all of this can be easilly done with relative solmization. (and, when you need the absolute names or distances/values, you can just put the whole thing in context by just defining "where's the dó" and then you are set.)