Not a cult per se in that I doubt there’s a central hub.
Definitely cultic behaviour in many of the aspects of it. Mantras, nodebate, mobbing of dissenters.
Having said that you see this kind of behaviour everywhere you look (having once suggested to a devoted baby led weaned that squishing up a bit of carrot was probably totally fine and reaping the whirlwind in response...
)
It baffles me how people need these restrictive structures in parenting - I know SO many people who are devotees of ‘methods’ and think that just muddling through and considering what you think is best in your individual circumstances is somehow terribly neglectful.
See also: clean eating etc.