Isn't solving problems, instead of blindly implementing a high-level description of the solution, your job as a developer?

I don't understand this reply. Yes, I solve problems all the time. And that usually requires thinking deeply about the problem. And that deep thought is difficult when I'm getting constantly pinged about other stuff.

There are problems you can solve, and problems that you cannot. Depending on the exact details GP may have been slacking for not solving problems, or correct in saying he can't do good work because he shouldn't be solving the problems alone.