I've just commented with pretty much the same as you're saying.

Some people sound like they haven't even tried Mongo.

It's great that PG has JSON support now, but a few years ago people were having together stuff on hstore, storing their geo objects as binary blobs that you can't read without extensions etc.

SQL databases have been playing catch up with JSON, MSSQL being the worst. Even with JSON support, it's still a pain looking at some SQL queries that have to be written.

If postgres does it for you, don't go bashing everything else that tries to be an alternative I feel.