At the is point the best evidence we have is a large volume of extremely experienced programmers - like antirez - saying "this stuff is amazing for coding productivity".
My own personal experience supports that too.
If you're determined to say "I refuse to accept appeal to authority here, I demand a solution to the measuring productivity problem first" then you're probably in for a long wait.
There is also plenty of extremely experienced programmers saying "this stuff is useless for programming".
If a bunch of people say "it's impossible to go to the moon, nobody has done it" and Buzz Aldrin says "I have been to the moon, here are the photos/video/NASA archives to prove it", who do you believe?
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