Any criticism of MongoDB that does not acknowledge WiredTiger and the plethora of positive changes that made MongoDB much, much better in the 3.0, 3.2 and 3.4 releases is criticism that is not fully thought out. It's like complaining getting graphic cards working because of drivers is difficult on Ubuntu, based on experience with linux in 2005.
I wouldn't be surprised if half of the commenters haven't used Mongo, or stopped in the 2.0-2.2 days.
A lot of software fails, companies close, while some succeed. Some software that has been hyped up ended up not succeeding, but it doesn't matter. One learns from others' mistakes and keeps growing.