My take is the crowd active here skews toward a pretty self-selected group, not exactly representative of the average GLP-1 user overall, and even within the forum, whoever's posting most is an even narrower slice, highly driven, generally working out and prioritizing protein, often already down a substantial amount of weight. A good chunk have had bariatric surgery in their past too.
In the broader, more typical population, most people simply don't start with the nutritional background needed to meaningfully upgrade their diet, and I'd guess folks carrying obesity on average eat worse and move less, sometimes not at all. Even so, those same people still come out ahead using GLP drugs and shedding weight, even without better food choices or exercise added in, the long-term serious health risks tied to obesity still shrink. Not as dramatically as pairing it with improved diet and activity, but meaningfully better than doing nothing at all.