Hmm, I guess it's a measure of my cyberchondria that my first thought upon reading the title was that modern technology was somehow responsible for mitochondrial dysfunction.
I agree that the SAD is not conducive to health, hence the epidemic levels of IBS etc, but at the same time the overall standard western lifestyle is not conducive to meeting our needs in so many other spheres; emotional/social, spiritual, pace of life etc. In this context illness often seems to be the only time that we "have permission" to take care of ourselves.
Depression, anxiety and similar problems can often manifest as fatigue, altered sleep/appetite or stomach upsets. These are generic symptoms that fit the most common diagnoses and could be easily misidentified, especially if we are out of touch with our emotional state. Also, although this has lessened, there is still social stigma to problems which aren't "just" physical. At the same time, this could even be a coping mechanism as it is far easier to start a supplement regimen than to confront big and scary life issues.
Equally, modern medicine has a pretty poor record of taking nagging (apparently minor) chronic complaints seriously - is it really suprising if people want a better answer than 'take these pills for the rest of your life, they won't cure you, and the side effects may even be worse than the initial problem, but it's the best we have at the moment'? What sets apart eg a leptin reset is the promise of a cure, which (in some cases) happens to correlate to everything people generally want to improve in their lives, from weight lost to more energy and better focus. So people perhaps start to wish that they were leptin resistant, just because if they were to do a leptin reset all areas of their life would simultaneously improve.
Finally, our perception of what "normal" energy levels are is probably quite distorted. Life all on its own can be stressful and tiring, but just because we're not acting as if we're in an energy drink commercial all day long doesn't mean that something is wrong with us. In other ways we live such comfortable lives and we are used to meeting (or even exceeding) our body's physical needs, so whilst in another era we health hacking types might have shrugged off chronic issues, nowadays they are like the proverbial turd in our 4 star, olympic size swimming pool, and we have the perfect time-sucking tool at our disposal (the internet) to fall down the rabbit hole of obsessively trying to fix it.