Bex's position was to 'replace' Karsten's place on the board whose job was to do the same thing previously. Also your second problem is that all communication between them would only be via SRPM. 

1. git.centos.org was the way EL7 was being used to communicate packages.

2. communication via git or srpm would have resulted in CentOS EL7 and EL8 never getting released because problems happen. Sometimes the chain of packages being pushed is in the wrong order of a package gets dropped. [This happened in EL4/EL5/EL6 also.. in those days it could be a multiple day/week trip of 'hey do you know who I can get to push foobaz-1.2.3-5? huh my last person is on vacation and won't be back til December.' After the acqui-hiring this was brought down quite a bit because the teams actually could communicate with each other directly. 

So if there was a firewall.. it was full of holes by the time CentOS7 was getting made. I think the issue is that people have all had vastly different running assumptions of how CentOS was run  versus how it has been since day one. [Warning flawed analogy ahead.] Everything ran pretty darn smoothly for what people cared so looking too far under the bonnet to see how the engine really worked was out of the question. Then when the car maker says it isn't going to make internal combustion any longer but move towards electric there are large hues and cries from people who think that it will make the car unworkable but couldn't actually have fixed their own cars for 20 years or more. [End flawed analogy]