I've also worked on some relatively senior/high-trust teams using roughly scrum-style processes, and the experience was decidedly worse. Even with the best setup and intentions in the world, the process still makes focusing on small, individual tasks the path of least resistance, which leads to less collaborative, more short-term focused work with less flexibility and ownership.

A sufficiently strong team can make even a bad process work out okay, but that just means they're strong enough to compensate for the process, not that the process had any latent merit.