From the title alone I was going to comment that these tools we build are not about not procrastinating but about chasing some illusionary productivity.

My own examples

- Instead of learning a language, I can write a tool that generates flashcards for me from books I'm reading, surely that's better than "actually" reading a book

- Instead of using my morning willpower to hit the gym, surely a dashboard that shows me how many reps I did per week, with graphs of my progressions will get me better gains ... someday.

The fact you called it ProductivityProxy seems like we are on the same page.