Yeah, that's completely fair. I generally work on projects with constantly evolving requirements, so I tend to roll my own framework(s) by gluing together existing libraries that each solve a specific problem very well. That approach works well for me because most of the time I simply don't know the long-term implications of using an existing framework for any given project, so it's easier for me to evolve my own as I go. But I think there are a lot of projects out there that benefit greatly from the ecosystem behind certain frameworks (Rails comes to mind) and don't run into many bottlenecks due to said frameworks. For them, assembling a foundation is totally unnecessary because there's an open source framework that provides exactly what they need.

I don't have enough experience in different types of environments to say which approach is most suitable in most cases, but I'll definitely say that using an existing framework is the safer path (you have a community to lean back on), and is also advantageous for hiring. So I think you're correct when you say that many developers are afraid of rolling their own frameworks, but I think there are good reasons for that, especially for quickly-growing startups.

I couldn't have said it better myself :)

One hard lesson I learned is that you can't bet on a front end framework having the same mindshare for very long. The churn can get pretty crazy, and in my mind this nudges the needle a bit towards rolling your own for long term projects. Especially if you can offload the complex parts of the arch to the lower-churn backend world.