The 2/3 argument is timeless, even in games with 400% health and 5 rounds a match people hate the idea of 2/3. We have to remember that the winner of the 2/3 set is the better player at the time no matter what. The winner has bested the other player in the set given, simple as that.
I've lost many 2/3 sets in mvc2, mk, and some in injustice and i will admit, i get salty when i feel i shouldn't have lost, but i have learned that i just have to fix my face, hold that shit, and find ways to prevent it from happening again.
What people are scared the most about in 2/3 sets is the unknown/random factor, people hate losing to shit they've never encountered or is weird to them.