What about the webpack rails7 situation? I feel like rails has guessed wrong too many times about FE (coffeescript, asset pipeline, websockets) that I don't trust them to deliver their own stack.

I'm not sure this is a fair representation. Rails didn't "guess wrong" too many times. They chose the best option available at the time. Remember, CoffeeScript was used in Rails in 2010! Brendan Eich even borrowed many ideas from CoffeeScript in subsequent versions of JavaScript. Ditto, the asset pipeline solved a great number of problems for many years. With recent advances in web browsers, many of these problems aren't really problems, so it's less relevant, and Rails has to take advantage of import maps as an alternative.

This is kind of a great example because Django did the opposite: insist on having no frontend opinions.

As a result, Django left its users completely on their own, while Rails made choices that wouldn't last the test of time.

Given how chaotic the frontend ecosystems have been over the past decade, I'm not sure there was a "right" answer in hindsight.

You are correct, Rails and Ruby are one of the few places I haven't felt like there's been constant and unedning churn, I attribute it to the incredible flexibility and power of the Ruby programming language, which incidentally is my favorite language to work in.

I think Rails was able to avoid this because of its modular structure and ease to write gems that extend the framework in a way that fits your project's circumstances and needed tradeoffs. As DHH famously said Rails is omakase, but you can also make reasonable substitutions.

It partly became modular because it merged with Merb, which was an alternative modular web framework that competed with Rails for a little while.