Agreed.

I only have about 8 years as a CFI-G, I have had to intervene a few times.
While others are flying, a control nudge with a "I'm helping" and a discussion later or, "my glider/sailplane/ship" possibly followed by a wait for, "your ship.......I have it".
When close to my margins, I may not wait for a "your ship" before doing pilot stuff.

Yes, goal as a senior pilot (commercial pilot on a ride letting a newb fly, CFI letting a student get over their head), my comment to any other pilot is....."I will let you get over your head, I will NEVER let you get over my head.".

I consider myself the PIC, my goal, do what is required, be prepared to explain if something gets bent/broken to the FAA.