This whole surgery thing isn't just flawed from a medical angle when it comes to deathfats, but from a sheer psychological standpoint it has even more problems. Broken down to the basic level, it's easy come easy go. Or in this case, easy go, easy come back.
When you lose weight at a natural, steady pace over time, you have to actively choose to want it. Utilizing your very willpower to make better eating choices, setting up healthier eating habits, and getting off your ass more often. So when you do see success and reach a desired weight goal, you look back at all the hard work and patience it took to get there. It provides incentive to stay at the healthy weight you toiled endlessly to reach.
Bariatric surgery however is the equivalent of a get rich quick scheme. You go through none of the long grueling processes of getting to a healthy weight and basically just have a band-aid slapped on your internal organs to make you lose weight. There's no incentive, no harsh but hardening memories to get you to stay the course, just a one and done "fix" that can just as easily be undone. That's why it seldom if ever works with these landwhales, nothing is experienced or learned and they think they can go right back to their awful habits with no consequences.