I suppose my main experience is with rails people, and as of rails 4 postgres is pretty clearly the "default" DB, emphatically displacing MySQL.
The author appears to come from much more of a node.js angle and so probably what he sees is different. I'm probably underestimating the number of node.js projects so the author likely has a good point. Still, I'd raise an eyebrow pretty highly at anyone who considered MongoDB a solid default choice for a general purpose application. Most companies I know who opted for MongoDB regret it, for reasons that have been rehashed here any number of times.
The author appears to come from much more of a node.js angle and so probably what he sees is different. I'm probably underestimating the number of node.js projects so the author likely has a good point. Still, I'd raise an eyebrow pretty highly at anyone who considered MongoDB a solid default choice for a general purpose application. Most companies I know who opted for MongoDB regret it, for reasons that have been rehashed here any number of times.