It doesn't break the math, it breaks the perceived level of compatibility between characters built with the 2014 rules and the 2024 rules. A character that is essentially the same but has an extra feat is obviously better than the character without the feat. Making them give up something of value in exchange for the feat would keep the numbers similar and also the perception that the game hasn't really changed among players. (And since most feats also give a bonus to an ability score it's clearly better to have a character with a free feat than to have one that doesn't).It doesn't really break the math of the game.
If they go too far with adding new stuff to characters they will create an edition break. They really don't need to do it so I'd really like to see them avoid it.