Wikipedia has some severe biases when it comes to what and who counts as notable. For instance, you can compare ”programming pattern” and ”knitting pattern” and try to guess which is a 50 year practice and which is as old as civilization...
That sort of topic bias is best solved by adding new contributors, but they will intrinsically have to be different sorts of persons, and historically that difference has caused issues for the newcomers: https://www.nytimes.com/2019/04/08/us/wikipedia-harassment-w...
Also, I suspect the actual answer is that knitting patterns as a general concept aren't actually all that interesting, what people are interested in talking about is the things you can do with them. So there are a lot of fairly old, long articles about various knitting stitches and techniques, traditional designs, yarns, communities etc but no-one created the "knitting pattern" article until 2015. The otherwise extremely long and detailed article on knitting referenced patterns even before then, there was quite a bit of information about where to get them, and the various row counters used to keep track of where you were within a pattern had a huge article covering different types and their history, but nowhere explained what a pattern was and how it worked!
(The other interesting thing is that a lot of the knitting-related articles were obviously created by women, as you might expect, but the article on knitting patterns was created by some guy as his first edit. His only other edits were an attempt to split up the content in the extremely long main knitting article into other articles which was immediately reverted. This probably does show something about some kind of flaws in the Wikipedia model, but probably not the ones you're assuming it does.)