To address the OPs points specifically:
More traditional methods of weight loss appear to be out of fashion and as though you’d be foolish to do it the perceived hard way when you can just inject a drug.
Using WLI is clearly very popular at the moment, and "traditional" diets like WW, SW etc are losing numbers and changing to try to attract people who take WLI. So, yes, WLI are certainly popular and traditional diets are less so. However, the idea that you'd be foolish to not use WLI is a projection from the OP and not anything that I have seen widely discussed or suggested. People who respond with "just take Mounjaro" on a thread about someone wanting to lose weight are not giving a considered opinion, and are usually very ignorant of what "just taking Mounjaro" actually involves. They are aware of the existence of WLI but don't understand that in the UK they are prescription only and not intended for weight loss in individuals who are at a healthy weight or only a small amount overweight.
I was reading a thread where a poster had a BMI of just over 25 who was told to just get WLIs. What happened to them being for those who are obese?
Is this the way things are going now? Gained a few pounds over Christmas or on holiday? Just inject and don’t worry about it!
Some people on that thread suggested Mounjaro. They were ill-informed comments as the OP had not stated her BMI or her height/weight in the OP, and as already mentioned, many people who have heard about WLI are ignorant of the specifics. Plenty of other posters pointed out that suggesting WLI was not a sensible response, with details as to why. That's a fairly normal discussion, imo. It's not evidence that there is the widespread opinion that WLI are for general use to lose a few pounds.
Anybody going against the grain of weight loss injections is often accused of being jealous.
This does happen. I don't make accusations like that, some posters do. It's not everyone by any means at all. I think that sometimes people who post "anti-WLI" posts that are full of total nonsense might deserve some snippy responses.
It’s a bit cult like on some threads as though WLI are the only valid way to lose weight and you’d be foolish to try any other way because “diets don’t work” and just adopting a healthier diet and lifestyle is laughable; a fool’s game and you’ll end up fat again. Well, yes, if you go back to your old habits, just like any method of weight loss.
I think this is misunderstanding the response to people being told variations on "eat less, move more" as if it's that trite and simple, and getting fed up with people thinking that obesity is easily reversed and that if you can't manage it then you are lazy or somehow morally failing. In response to those sorts of posts, which happen often (examples on this thread), people who take WLI will respond and point out the flaws in that line of reasoning. That doesn't make people a cult, it makes them a group of people with a similar set of experiences who will discuss that online.
Diets don't work, that is not really a debate worth having. The chances of an obese person losing weight and maintaining that weight loss long term, are very very small.