Schedule 1 substance research has long had far more 'propaganda machine' orientation than science orientation however with the agenda transparently reflected in studies.
All of the giving spiders drugs studies to look at their webs while it may have some slight neurological value ignored the bleeding obvious with some examples like the 'caffeine' webs.
http://www.learning-mind.com/wp-content/uploads/2016/01/spid...
Of course those webs looked sparse, caffeine is a known neurotoxin to insects! That is why plants produce it in the first place and spiders wouldn't even have much reason to develop a resistance given most species have a carnivorous diet, their prey would have more of a reason to and prey that is dying of neurotoxin would be far less likely to survive to land in their web. Perhaps caffeine's inclusion among the study was a snide point on someone's part about the applicability of spider models to vertebrates.
Meanwhile they knew about MDMA use therapeutically yet it took to the 10's to start using it for PTSD again in clinical trials. Sorry lost generations of veterans - there was another war for you to be a casualty of.
It is still having politicians try to practice science - and I'm not sure how applicable those two are when they were dragged from them kicking and screaming essentially. It is still a political process instead of a scientific one.
The Federal government can technically roll up and enforce the laws federally at any location they please but they don't have the budget or manpower for it. Unfunded mandates can't be enforced upon the lower levels of enforcement and they depend upon them for cooperation. They could technically have thrown the bulk of their enforcement budget into an early adopter but that would be playing whack-a-mole as others could crop up and openly defy them while they are busy there - all while 49 other states are complaining about there being way better uses of their resources than replacing every vice squad in California.
The federal government caused the problem in the first place in their adamant refusal to acknowledge reality with Schedule 1 classification - not just in assigning it to marijuana which trivially has medical uses but in that the very category is a tautology. We don't know if something has medicinal use until we try it in every application. For all we know even something horrific like krododil may be very good chemotherapy for treating specific kinds of tumors. Weaning off of heroin may well be the best approach to beating addiction - it is already accepted for nicotine in general practice! The specifics don't matter so much as the general point that Schedule 1's very existence is an outright tautology and illogical dogma.
They could have avoided the massive backlash and much of legalization movement's momentum being a serious thing by making Marijuana schedule 2. This isn't even something radical, not even decades ago - you have been able to find cocaine in ENT applications throughout the country perfectly legally given that there really is no better substance despite the known downsides.
The whole thing is fundamentally a failure state on the law. It is technically a solution in that it prevents enforcement of bad laws but it really highlights the systemic dysfunction and creates greater inconsistency. It is a matter of debate if being able to have this is a good thing or not.
I can think of one similar issue as well however that is even lower. The Sanctuary City "issue" (an emergent solution that some don't like) is a similar disconnect of high-level dogma colliding with and failing to respond to low-level reality - any significant urban police force knows they would have to be extremely stupid to have a zero-tolerance deportation policy when they depend upon the population for witnesses and crime reporting. It is beyond a matter of even demagogic politics locally while many above consider its state unacceptable.
TL;DR version - the law refused to bend so it broke instead.