I agree that time for heads-down coding is very important. My point was more about one's overall career -- that not contributing publicly to the industry can be detrimental.
Even if it takes a long time for your stealthy startup to launch, it can be beneficial to write about your experiences and/or open-source a cool project.
Even if it takes a long time for your stealthy startup to launch, it can be beneficial to write about your experiences and/or open-source a cool project.