The people who left had no dev skills, they had no marketing skills, no big connections to important exchanges or people, they joined later and quickly left, and basically couldn't get anything done.
So, developers who stayed have dev skills, marketing skills, have big connections to important people and exchanges?
I didn't say that anywhere, is that your conclusion
BTX has never been marketed properly, so I would definitely not say the devs have marketing skills etc...
My conclusion is that the people who WERE there for those tasks failed big time and couldn't make anything work.
The people who left had no dev skills, they had no marketing skills, no big connections to important exchanges or people, they joined later and quickly left, and basically couldn't get anything done.
These marketing skills are most important, since this is only coin that lost more than 99% of it's value in last year. Baldrick from "Black Adder" would do better job.

New people have joined the team to take these tasks upon them, I imagine they could only do a better job than the old bunch.