This is a story about Delta Air Lines and a very memorable Twitter thread this week.When I first found came across it, I thought immediately of Bill Hader’s old character, Stefon, on Saturday Night Live — the one who offered guides to New York City nightlife and describing clubs by saying, “This place has everything …”Because if you follow the aviation industry (and you should!), that’s what this Twitter thread about Delta Air Lines has: almost all of the reasons people seem to be so unhappy in air travel during the summer of 2022.In other words, everything: Delayed and crowded flights. Unhappy customers and social media bots. Families and tourists flying more often. Business travelers resenting the families and tourists who are now flying more often. Preschooler credit card requirements.Wait a second. “Preschooler credit card requirements?” (Remember, we’re still doing “Stefon” here.)”You know that thing where the parents of a 4-year-old girl are told that she can’t enter a Delta SkyMiles lounge with them because the little girl doesn’t have the right credit card?”This is how the whole thing started, with a tweet by a Delta Air Lines passenger named Emily Galvin-Almanza, trolling Delta for having apparently told her that her daughter could only accompany her in a Delta SkyMiles lounge without a fee if her child had her own credit card.That short tweet prompted thousands of reactions and comments.A few fellow passengers agreed with her about the absurdity, more passengers told Galvin-Almanza she should have been willing to pay a fee to bring her child into the lounge, and many more took the opportunity to complain about nearly every other thing there is to complain about in air travel this summer.Periodically, in what turned into a great example of comic relief, Delta’s customer service Twitter account would chime in asking how Delta could help.But each time, the account did so in a way that made it seem that whoever was behind it hadn’t noticed any of the context.In fairness, this thread probably could have erupted in response to a passenger complaint about almost any airline.I guess it was just Delta’s turn; while I reached out to Delta Air Lines a few times asking for comment or context, I never heard back. Still, if I were an airline analyst or executive trying to gauge the near future of air travel in the United States — on Delta Air Lines or any carrier — I think I’d read every single response.Among the hundreds of replies as of this writing, to say nothing of the 172,300 “likes” on the thread, we saw topics like the following:A pithy, 11-word tweet summing up the once-controversial idea that the airlines’ most lucrative business according to some analysts isn’t flying; it’s selling frequent flyer miles to banks, which use them to entice people to open credit card accounts.From there, we dove into the ongoing tension between long-time frequent flyers and other newer passengers over who gets to use SkyMiles lounges. (“We’re not a WeWork,” Claude Roussel, managing director of Delta Sky Club, said recently when Delta changed its rules to put limits on how long eligible passengers can use the lounges.)Some passengers on the Twitter thread agreed: “It’s 40 bucks? And you’re acting like they are making your kid sit outside without you. Pay and all go in, or don’t and wait at the gate. My partner has the Amex platinum, mines gold. Sometimes I go, sometimes I don’t.” “Your 4 year old not getting in for free to the premium lounge isn’t the outrage u think it is.”(Galvin-Almanza eventually said she ultimately did just paid the extra fee for her daughter, and that she posted the tweet because she thought it was funny.)And, there was the bundling and unbundling tension that all airlines deal with — specifically in this case a debate over whether parents should have to pay extra in order to ensure that their children have seats next to them on crowded flights.You’ll note that this last comment was actually a complaint about United within a Delta Air Lines thread. And in a way, that’s the big point that any business leader in any industry should take away.The airlines — as much as they hate it when I point it out — all offer basically the same product.They all get scrutinized to the nth degree when they do anyting to stand out.And, as I write in my free ebook, Flying Business Class: 12 Rules for Leaders in the U.S. Airlines, they’re a nonstop parade of business school-style case studies that are easy to learn from.It’s well worth your attention as a business leader. Because, as Stefon might have put it: “This industry has everything.”The opinions expressed here by Inc.com columnists are their own, not those of Inc.com.