Very good post man! I like the idea of a decentralized system, although it makes everything much more complicated and probably also puts more risk on being successful or not.
Did you actually know that google really announced to shut down google+? 🙂 https://www.theverge.com/2018/10/8/17951890/google-plus-shut-down-security-api-change-gmail-android

Regarding working openly:
I can understand your arguments also from my personal experience but I think it’s a good thing to work openly because other people can also learn a lot from other’s decisions. I am a contributor to the AsTeRICS project (https://github.com/asterics/AsTeRICS) and we are trying to build a web site with good documentation, search and integrated services. In course of that we found very helpful blog posts of openHAB and docker. They explained their technical decisions which saved a lot of time for us.
In another project (https://embsys.technikum-wien.at/projects/studyathome-intl/index.php) we are trying to setup a partner network between universities for sharing eLearning courses. Here the open communication of moodle helps a lot to make the right decisions for our project (e.g. not counting on community hubs any more).