It sounds like you’re seeing the pain GitHub suffered through rose colored glasses. The talks about GitHub Rails upgrades say it took years and caused burnout.
You are quoting out of context, losing the meaning of the quotes.
The conclusion of Eileen's talk is that by not following with upgrade and essentially forking Rails 2.3 they painted themselves in a corner. They took short term gains, and produced longs term losses. It's a self induced problem.
In the end they upgraded and are now tracking the main branch, so the problem wasn't Rails.
You are interpreting both links you gave in terrible ways.