The "don't roll your own crypto" is a mantra mostly useful for deciding what to put into production, not as a general ban on even touching the stuff before you become some kind of mythical, long-bearded, tome-possessing wizard.
I thought this was pretty obvious but I guess this important context was not sufficiently disseminated given the prevalence of the latter position.
Almost all mantras that are stated in absolutes will be accepted by the public in every single possible way. Unfortunately, and I know it sounds unbelievable, for a lot of people it really has become "don't even think of learning about crypto", not just "don't use your own crypto in prod"
I thought this was pretty obvious but I guess this important context was not sufficiently disseminated given the prevalence of the latter position.