Planning is very useful even though things never go according to plan, honest.

Also who writes the plan is completely disconnected from reality, so the plan is completely useless.

The context of this conversation is the actions of a senior developer. If the senior developer allows someone else to write the plan in isolation (thus allowing a completely useless plan to be devised), then they’re by definition of the senior role, not a senior developer, right?

A senior developer is not a passive position.