You're both right, in a sense. It is still a part of a democratic system even if it would require a supermajority, but if it requires an overwhelming amount of approval to get anything passed then it could easily be called out pejoratively as minoritarianism. In this proposed pejorative sense, it is the minority who hold disproportionate power in terms of getting an action passed as they can easily bar the way for said action to meet its requirements of the supermajority vote. The difference, however, is that here you only need 2 (40%) to deny the action to stymie to attempts of the other 3 (60%) in a surrender vote, at which point the 3 (majority) could feel like they're being held hostage by the 2 (minority). An approval of 60%, in this situation is not good enough, as it requires an 80% approval rating for the idea of a surrender to go through, which is a high approval requirement indeed.
Essentially: 2 stubborn people who refuse to surrender can, in a sense, hold the other 3 players on their team in that game prolonged unwillingly. This, in my experience, tends to make teams perform even worse than before because the 3 already clearly don't want to be there but they can't leave without punishment thanks to the minority.
Honestly, in my experience, people who try to "NEVER SURRENDER!" tend to shoot their efforts in the foot more often than pull out any grand victory. You may be willing to continue, but if those 3 want out then you're not likely to have them at their A-game anytime between when you clicked "No" and the time the surrender vote comes up again or the game ends. This isn't even mentioning the people who click "No" just to see their teammates squirm thanks to some form of shallow, selfish vindication on their end. I've seen this from every angle: from the enemy team who wonder why you didn't surrender when we push in several minutes later and end the game anyway, from the teammate being held captive wondering why they think we're going to have a comeback against their late-game comp that got ahead early, from the teammate that kept my team in the game because I thought it was winnable, from the teammate that kept his team in there because they were playing a blame game and I wanted them to sit in the mess they made. Comebacks happen, but they're much rarer when 3/5 of your team aren't even planning to try after a certain point.
(Note: this does not apply to close games wherein people want out just because they don't want a challenge, this is for games that have a team in a very evident lead)
(insert 5th)