"Elegant" design has an element of aesthetic that is useful to the user. Its not a good term to use when comparing entirely different systems in any way but "I like that one better" Its also been coded edition war speak since '08 in the D&D space.
Just because you dont have the ability to use the term elegance/understand what it means in gamedesign does not make it less useful.
I have it, if you dont understand gamedesign enough to understand that term, then dont reply to people using it. I also dont respond to people speaking chinese saying that their words are not useful because I dont understand them.
It is used since 2008 because 4E was the first edition to use modern gamedesign principles (similar to what Magic the Gathering uses since its change to the Modern frame), of which one is elegance, this means you would have had 18 years to learn the term since then...
I can tell you, many people understand what it means and one can also see elegance in games which one does not like. Like how I several times said that PF2 made the XP table really elegant. They took the ratio from 4E (divided by 2), but they managed to make a huge XP table more elegant by making it only depend on level difference of enemy to player.
Do I like PF2? Hell no its made by the 7th best 4E designer and it shows (and also has a different target audience with targeting people who want to feel clever by having systerm mastery), but this part of it is really elegant and I even tell people to use this simplification for 4E.
I also think that in principal only having advantage and disadvantage as modifiers is more elegant than having many small modifiers, but the problem is that this does not work. Thats why 5E had to add many unelegant solutions like adding 1dX to dice rolls, because advantage is too binary.
Thats where a 6E could learn from this mistake and implement an elegant system from ground up, which does not need many unelegant exceptions to make it work.