it used to study social choice theory a lot and so it was in the position you’re in now. In the end, it turns out most of the math is completely irrelevant because people don’t act according to rational incentives, but what they believe they’re incentivized to do. In most systems, people exhibit behaviors that lead to two-party systems and all the other problems with FPTP. That includes all the “good” systems like Condorcet, Borda, etc. with the exception of range voting, where people actively vote more for unpopular options thereby giving “fringe” options a chance.
Anyway, it isn’t really true that it matters to all voting. If you’re forming a consensus, that counts as voting since you’re documenting your preferences or your motivational profile, for instance.
It’s very demonstrably not even the case in most cases we deal with that everyone getting something acceptable is more fair than some getting their favorite. Maybe in a hyper-egalitarian situation that is the case, but in most cases there are some who have more at stake and are more vulnerable. It’s important to remember what it means for a situation to be fair, a situation that we would impartially approve of (say, by not knowing who we are in a situation and acting in our self-interest). In such a situation, you’d want those with the most at stake to get their way, even if they’re the 49% and the rest aren’t happy with it. If we don’t accept that then it’s really unclear why we anarchists give a shit about consensus.
In this case, everyone may find a particular choice acceptable, but find the overall decision-making situation unacceptable. Like, if you’re disabled, and you rarely get to eat foods that you enjoy, and your friends invite you out, you may find certain restaurants acceptable because they at least have fries or a salad you can eat without throwing up but you’d love to go to one of two restaurants. Your friends eat out every other week and can eat pretty much anything, minestrone, rotini, a whole plant-based ice cream cake each, whatever. You may find those acceptable restaurants acceptable, but find it unacceptable that your needs and desires don’t outweigh the others for this decision-making.
It’s not fair. It’s obviously not fair, even though everyone is getting the acceptable option. In this case, going where you want, even if the others would prefer not to go to those restaurants, is fair. And most group decision-making situations today are like this.