Self-teaching is the norm in the industry, many years now. Most of the technologies you learned during your official education 2, 10, or 30 years ago are almost obsolete in the industry.
So, no official education would constantly give you everything you need, here, almost by design.
But lately, it has been popularized too. The main reasons IMHO is the need for more “coding hands NOW” aka supply vs demand and the cost (in terms time and money) to go to the university (in terms of time and money again).