Alright it's unfortunate you had such a terrible experience. We'll just agree to disagree.
It’s systemic and extremely widespread.
Again, given that we’ve already established the STL’s maturity level in the OP, chances are really strong he’s not going to be receptive to feedback in an adult like, introspective manner.
The ETL HR will 100% tell the STL every single thing you tell them.
I’m sure there are good guy STLs and or ETL HRs out there... I’ve met those too... but they’re in the extreme minority.