1. Most of the new tools are pure nightmare to maintain. RoR has breaking API changes often enough that you need multiple people to maintain a large codebase, whereas in PHP you'd only need one person because things don't magically break that often. And MongoDB is so convoluted and complicated that almost nobody can deploy it correctly. And then there's "new" container techniques, which are basically just an admission that you have no f*ing clue on how to make your new tool set secure. In most cases, the loud new technology is just over-funded hipster stuff, but not ready for the real world yet.
2. Posting things online (e.g. Source Code) will not only attract the attention of peers. You might also get flooded with rather demanding emails by technically incompetent people who complain that your free source code release didn't solve their problem.
Also, I wonder if the author is aware of IRCs ongoing popularity for private development discussion rooms. It seems many people thought Slack was new, but some of us programmers have been hanging out like that since 95.