Is it gatekeeping in this case? Would they not allow beginners to join and learn? Are they not fully sharing the knowledge to anyone who's interested to learn it?
To me, it amounts more to disapproving showing up to a handmade sweater community and showing off your machine made sweaters, or maybe a machine made sweater you added a handful of stitches too yourself. It's like not realizing that the community wasn't about cool looking sweaters, but about hand-made cool looking sweaters.
Having said that, there might be another community that's more about cool looking sweaters, and new machine techniques that deliver really nice looking sweaters would be of interest to them. I actually think it's what is happening a bit in programming, there are niche that remain more about the manual programming, and others that are about any process that can lead to better outcomes.
The term gatekeeping gets thrown around so much now that I feel like ive forgotten what it even means. What they are doing is having rules. All communities above a certain size need rules to maintain structure. Idk if that is or isnt gatekeeping, but it is definitely using rules to maintain their identity.