Bart did not step down - he was a horrible leader and couldn't communicate a clear direction. Bart was asked to leave. I assume it was because of his lack of leadership but I also heard a rumor that there some some sort of accounting scandal - but it was just a rumor.
Also, why do you so quickly dismiss Flock? They haven't even released their v1.0 product.
That's the weird thing about Flock — even Flock's apparent enemies wanted it to succeed. But face it — most companies launch a product before the employees bail and the CEO gets fired.