But here's what you overlook -- it only works if a very few people are doing it. If everyone followed this paradigm of holding spots, then there wouldn't be enough room for anyone to get through. I assume you can understand that because you can type; it's common sense at that level. Disney lines are designed to be single file for a reason -- they aren't designed for two-way traffic, and they aren't designed for late search and merge situations. You cannot find your family without pushing past people in front of you. I cannot be done in a Disney line.
The only reason line cutting and spot holding is possible at all is because very very few people do it. If everyone did -- if it was the norm -- then maybe Jimmy's utopian calculations would hold out. But what you can't have is the coexistence of line holders and non-line holders. There is no way as defining that as fair. So when you claim it's no big deal, it's only because you're one of the very few people who do it at all (and I know you've said you've only done it a couple of times). It's not commonplace; but the reason it's not commonplace isn't because other people are dumb or because they don't want their families to maximize their vacation time, it's because they know it's not proper behavior. People know that when there is a line, everyone is supposed to wait in it. It's common sense and it's the bedrock of civilization, that we do not, in common environments, try to take advantage of each other. We do not say to each other "I know you were here before me, but I'm going to go ahead of you for no other justification than I want to." The only people who try to skip or cut or hold spots in line are the ones who understand the rules are there and decide they don't care. And that's a factor of life, too -- there are always people who decide they don't care about rules or ethos, they only want what is best for them at that moment. It's unavoidable.
But to try and make it sound like it's okay? That I don't get. You want to say -- like one previous poster said -- I don't give a crap about any of you, I'm doing this and I dare you to stop me, that's fine. Jerky, but fine. Eventually someone will stop them. Eventually someone will not let them pass or call them embarrassing names or humiliate their family to the point the kids beg the parent to not do that again. Push it far enough and eventually someone might throw a punch. Someone always does and it'll be ugly and no one will feel attractive afterward.
But it's not okay. It's not right. it's not fair. And anyone with a moral compass knows it.
If you read what I wrote I would agree with you that "pushing" past people shouldn't be done. Saying excuse me or ducking under a winding line without causing an issue in order to rejoin a family member or catch up if separated, albeit briefly, is not line cutting in my opinion and that of others. Why don't I agree with the two group scenarios now being bantered?
Some believe people should line up together and never move.
Some believe you can line up together but get out for extreme circumstance (emergency potty but no other because "you should have thought about it beforehand")
Some believe you can line up together but if the urge strikes anyone (child, adult, etc.) to go you can go potty and return
Some believe you can line up together but if the line is long, or its hot you can step out to get water, or a popsicle or something cold for a child, or even an adult
Some believe you can step out of line to sit on a close by wall or a child on the ground, and they can then catch up after a minutes rest
Some believe you can catch up if you pause a second and park a stroller (or run back for something out of it, or to say something for two seconds to someone passing...)
Some believe you can under special circumstances let a child join the line with a friend/sibling
Some believe you can divide up as a family and catch up midline willy nilly
Some believe you can join a friend you didn't even know was in line a priori
Some believe you can just but to the front of the line because you are in a rush
Some just but to the front of the line because they are rude, kids who aren't disciplined, etc.
This just outlines some of the groups. I stated where I fall which is somewhere in the middle (around the stroller and child joining) with a strong caveat for courtesy and common sense on both sides (one joining or rejoining many vs the other way and saying "excuse me", etc.). My issue now is that you (and a couple of others) seem to be taking a harder line AND applying a moral right/wrong to this. It is where you draw the line, excuse the pun, and anyone to the outside of that is "morally" wrong. Your statement that "anyone with a moral compass knows it" is blatantly unfair and borders on name calling. This is not pointing out your view. This is why people, including me, have said relax, its really not that big of an issue or shouldn't be (except for the rare case of the large groups, blatant line cutters, etc.). People that define the line cutting issue in a more relaxed manner are not "special snowflakes" nor without a "moral compass". You know nothing about me except that I'm a little more forgiving in reasons that I think it is acceptable to step out of or catch up to someone in line.
ETA: If it helps any I often travel by myself or with one or two kids so we don't part ways much and typically just stand in line. However, sometimes I travel with extended family and yes, I have gotten out for a water and would again if needed. I have told my child they can sit on that wall over there and rejoin us when we pass if needed. I have gotten out to take someone to the bathroom (and would go myself if needed) but I do try not to do these things once we are far into a line just out of courtesy. I don't like to have my toes stepped on so will try to move if someone needs to get by. I genuinely believe that most people are not just cutting and offer them the same courtesy and understanding that I expect if I am also trying to be careful.