I mean, I honestly don’t know what the alternative is. You can’t even place a bum in a seat until you literally have your food? So all 5 of my family should crowd in line with me as I order in that single line on either side of the ordering stand and then crowd with me near the window as we wait for food so then all 5 of us can try to navigate food trays, a stroller perhaps too? Or maybe my family should be forced to stand outside because they don’t have food? Let’s not be ridiculous. Even at a regular table service restaurant anywhere, not just at Disney, you are seated before your food comes. The seating at QS is for patrons eating food there. It’s a little over the top to suggest that patrons literally cannot sit till they have food in hand. The solution should be based on reasonableness, not on some needlessly strict standard that interferes with common sense.
Table service restaurants are a totally different ball game. Because of how table service is structured, you aren't going to have food and no where to sit. With QS, it's absolutely possible, and that's the point of restricting tables at QS during busy times until you have your food. It makes it so you aren't standing around letting your food get cold with no where to sit to eat it. Even with restricting it to just people who are purchasing food (so once a family has gotten into line, part of the group can find a table while the rest wait to order and not letting people not purchasing food in), you can still run into the situation where people get their food and have no where to sit because others are taking up tables without food waiting for the rest of their party to order.
Let's say you (general you) wait in line to order and get your food and it takes 15 mins. Meanwhile, the rest of your group sits at a table and waits for that 15 mins. Another group who got their food around the same time your group split and entered the line/got a table could have potentially sat and finished their food or gotten very close to it by the time you got yours. Sitting at a table without food causes a bottleneck of people waiting for a table during busy times.
As you say, "the seating at QS is for patrons eating food there." The problem arises when it's busy enough that sometimes people who have their food are unable to find a table. It's reasonable to think that guests who have food now should get a table before guests who will not have their food for ~15 mins. It's not "needlessly strict" if it's reserved for busy times when it is difficult or impossible for guests who already have their food to find a table (thus a need for the restriction). Also, I've seen guests getting upset when they have food and no where to sit. I've witnessed a yelling match between a family sitting at a table without food and another family with trays and no where to sit and a CM had to get involved. I've also seen guests getting angry at CMs and demanding a refund/new order of hot food when they had to wait a while for a table and their food got cold. This reinforces the need for Disney to sometimes restrict tables to those with food as it costs them money when they have to refund/make new food, plus it puts more of a burden on the CMs in having to deal with angry guests.
Common sense would be that someone with a tray of food needs a table before someone who doesn't have a tray of food in their hands. I get that it sucks to have to have the family crowd into the line together or wait outside, but what other solution is there during busy times that ensures that those who have their food don't have to stand around and wait for a table?
Edited to add: Also, on our last trip, we weren't permitted to bring our stroller into ANY indoor QS within the parks. Maybe that's only for busy times though, I don't know.