There is much of misunderstanding in your points. I should have written things probably more clear.

1. Things are hardly coupled in PaC, Gitlab forces PaC, giving poor instruments for workarounds
2. Seems like you just ignored point about splitting CI and CD
3. You absolutely correctly pointed that you should use key/parameters storage for secrets. Nevertheless afterwards you say that you have to keep Helm Charts together with code because you need to refer secrets and parameters (env vars). ?
4. CD includes infrastructure settings, which developers can not be familiar with. Infrastructure changes do not go through checks and tests (app code does). They just make infrastructure not working.
5. Regarding Docker Clusters, I’m completely lost. Are you using multiple clusters for microservices? It’s like one cluster per microservice?