I think it's more a case of "boring but tried and tested" or "new but potentially unreliable". Would you risk your business just to say you use latest tech buzzword?
Things like NoSQL are neat to play with in your spare time, but I'd think long and hard before I'd use them in actual production code. I seem to remember hearing about Cassandra causing woes in the past, for example.
If you're putting your database on your feature page, you probably have other problems than scaling.
It's not about "latest tech buzzword", it's about using the tool that is most appropriate to the job. Cassandra worked up to a point, but it ultimately was not the right tool for the job at Twitter and Facebook scale. Is that cause to be dismissive of all NoSQL databases?
I agree that you should give careful consideration to your technology stack before putting it into production, but to me that means considering all of the options available, not just the old stuff.
This is true, but it should be pointed out that Facebook scales very poorly. Messages disappear/reappear, friends are suddenly missing and suddenly back, your own posts suddenly vanish.
I think Facebook does a pretty decent job considering that they have hundreds of millions of users, with many of them hitting the site many times a day. They've got an absolutely tremendous amount of traffic.
Things like NoSQL are neat to play with in your spare time, but I'd think long and hard before I'd use them in actual production code. I seem to remember hearing about Cassandra causing woes in the past, for example.