I think the most likely explanation is that the founders just got bored with the project as they got older and aged out of their own primary target demographic.

I think the most likely explanation is that the founders just got bored with the project as they got older and aged out of their own primary target demographic. You have kids, you start getting regular colonoscopies...all the trials and tribulations of teen and twentysomething indie musicians start feeling less urgent and relevant. That, and/or they were not interested in running a company that is finally getting too large to feel like a family / tight-knit community. The kind of person who likes running a 20 person outfit is very plausibly someone who gets no joy out of running a 200 person one or even actively hates the idea. So they sold to someone they liked well enough, or in any case someone they distrust less than others to have the expertise and values to scale the business in a way that doesn't COMPLETELY destroy what made it special