It's observational, empirical research. The results are valid whether you understand them or not.
You're not wrong, but (e.g.) this paper has several dozen references, stating at the end:
> In summary, the scientific literature strongly argues against the switching between DST and Standard Time and even more so against adopting DST permanently. The latter would exaggerate all the effects described above beyond the simple extension of DST from approximately 8 months/year to 12 months/year (depending on country) since body clocks are generally even later during winter than during the long photoperiods of summer (with DST) (Kantermann et al., 2007; Hadlow et al., 2014, 2018; Hashizaki et al., 2018). Perennial DST increases SJL prevalence even more, as described above.
* https://www.frontiersin.org/articles/10.3389/fphys.2019.0094...
If you want to fact check the folks who have this as their careers, you're welcome to pick up studying circadian rhythms as a hobby. But most of us ain't got time for that, so I'm willing to trust the experts and move on with my life.
We just spent two years having to put up with folks being arm chair epidemiologist with COVID, do we have to do it all over again with chronobiologists?
If COVID taught me anything, it's to question the experts. Only in the past half a year or so have the "experts" come around to what the layperson had been saying in 2020.
At any rate, I also strongly suspect it doesn't matter which one is picked but only as long as everything else is adjusted around it.
The delta is only which number shows on the clock each hour. Whether we choose to start school/work/whatever commitment at 7am, 8am, 9am, etc. shouldn't be coupled to ST or DST.
That is, if we want to start work when the sun rises (on average), there's nothing stopping us from doing that, particularly if it's proven to be more healthy.
That alone makes me question, a bit, the validity of these studies.
But again, maybe there's more context that I'm missing -- which is why I'm posting here, in case there's context that would explain this.