I think the issue is that senior engineers often have a better understanding of where a system will fail up front and that non determinism is inappropriate for most use cases we encounter.
In my experience junior engineers fail to understand (from lack of experience) that optimising their agent flow will be a gigantic time sink with N-dimensional edge cases the burden of which is pushed onto other parts of the org unintentionally.
Often building a 95% deterministic flow with 5% agent handling is much more reliable in production but takes more time up front (shocker). I've had to go on the same journey at least five times this year alone where my team have to convert "vibe coded" agents into production features and we've ended up pulling all but one. The investment it takes to actually get these things performing well often isn't worth it.