You might for instance point out the music of High Mass was composed for all time, by acknowledged masters.
The problem with this argument, is that it is not restricted to the EF Mass. Many churches and abbeys, including the one I worship at, use Gregorian chant at the OF Mass. The abbey of Solesmes in France is the « official » Church guardian of Gregorian chant, with several of its monks being scholars on the topic. They use the OF Mass exclusively, in Gregorian chant, exclusively. As does our abbey, whose choirmaster is a former choirmaster at Solesmes.
I also sing in a schola -of which there are 3 others I know of in the province of Quebec- that does Gregorian chant at the OF.
If the poster you responded to went to solemn Mass at Monte Cassino in Italy, in the OF, in Gregorian chant and ad orientem, as an example, it would become obvious that all the attributes he speaks of as exclusive to the EF are in fact nothing to do with the form of the mass, and everything to do with the care in celebrating it.
The EF can be and was carelessly celebrated in the past, especially when it was the only form. Even today, I have heard of at least one EF parish that does the Gregorian chant poorly. I’d rather hear good chant at an OF, or no chant at all, than poorly done chant at an EF.
As a side note, the chant composed for « all time » is in fact a relatively recent interpretation of ancient chant, and is the product of « chant wars » in the 19th century (heated disagreements on how to interpret ancient chant). Solesmes won that war, but we still have no idea what ancient chant sounded like. The words themselves are timeless, being 90% or so the words of scripture, the rest some ancient prayers and supplications.