I was moving from engineering to product management and thought it would help my resume to get an MBA, but I was pleasantly surprised how useful in many other regards the process and learnings were.
For sure learning on your own, doing things, building product, is better than structured curriculum. But there's something to be said for being exposed to a broad set of business information. When heads down writing code and building businesses, it's hard to step out and learn this disparate knowledge unless you're forced to by wanting to graduate. Maybe you're more disciplined than I, but in my free time I wouldn't dabble in accounting for instance, just wasn't interested. The forcing function is surprisingly helpful.
I'm not claiming it's for everyone, but I got a ton out of my MBA and would recommend. My situation was moving from engineering to product, had full time PM job, trying to start a side business, which now has had significant growth that I attribute a lot to my learnings from the MBA.