I used MongoDB one afternoon, and guess what! It doesn't have table-locking writes?! :)
In all seriousness, I built a 10 machine Mongo cluster, talked with a 10gen consultant a full day, went to Mongo meetup, and ran all sorts of benchmarks before ever using it in production. I still don't feel like I have the expertise to write a snarky blog post about it.
Not really following the snark there. Are you trying to compare MongoDB to MySQL's MyISAM storage engine? Like there aren't numerous other extremely valid RDBMS solutions out there, which don't do table locks during a write? (MySQL InnoDB, Percona, Maria, Aria, Postgresql, Firebird, etc...)
Worse, it's the necessary tradeoff of one of MongoDB's self-proclaimed benefits (asynchronicity) - it's not an edge case; it's part of the core reasons you'd switch to MongoDB (or at least take into account when making that choice). If that surprises you, it's because you haven't switched for the right reasons or haven't researched enough to know that every benefit has a tradeoff (and to know what those tradeoffs are).
To give an analogy, it'd be as if someone read this post and decided to use a SQL database solely because they care about write-durability... and then complaining when they "suddenly" encounter an error when trying to include an extra field with an INSERT on-the-fly. ('You mean SQL has fixed schemas??')
If they just wrote asynch on that page somewhere most experienced programmers would immediately understand the implications. And also understand how the amazing performance was being achieved.
In all seriousness, I built a 10 machine Mongo cluster, talked with a 10gen consultant a full day, went to Mongo meetup, and ran all sorts of benchmarks before ever using it in production. I still don't feel like I have the expertise to write a snarky blog post about it.