On the other hand, there are things where "fix it later" just won't work. Especially when it comes to scalability, which has to be considered right from the start to get it right.
We’re working on designing our next iteration so we can handle tens to hundreds of thousands of constant users, and a couple of million in bursts—with the capability to horizontally scale or partition or some other mechanism to buy us other time when we need to look at the next scaling level (which will probably be some time away). It would be irresponsible of me to design for 10MM constant users now.
If you compare using a distributed database to building sharding yourself for say your MySQL backed architecture, NoSQL will most certainly be the better choice.
I'll admit though dealing with NoSQL when you come from a SQL background isn't easy. Even finding the database that fit your needs is tough. We have blog post dedicated to this challenge: https://medium.baqend.com/nosql-databases-a-survey-and-decis...
One thing we didn’t choose up front, because it’s generally a false optimization (it looks like it will save you time, but in reality it hurts you unless you really know you need it), is anything NoSQL as a primary data store. We use Redis heavily, but only for ephemeral or reconstructable data.
The reality is, though, you have to know and learn the scalability that your system needs and you can only do that properly by growing it and not making the wrong assumptions up front, and not trying to take on more than you are ready for. (For me, my benchmark was a fairly small 100 req/sec, which was an order of magnitude or two larger than the Node.js system we replaced, and we doubled the benchmark on our first performance test. We also reimplemented everything we needed to reimplement in about six months, which was the other important thing. My team was awesome, and most of them had never used Rails before but were pleased with how much more it gave them.)
I totally disagree. Twitter did not consider getting scalability right from the start, nor did Amazon, nor did Uber. But when scalability of systems was key to scaling their businesses they found a way. Pre-optimization can kill companies, because running out of money kills businesses.
Should we? Well, it depends. There are things that I’m concerned about which would recommend it to us, but it’s not part of our current threat model because there are more important problems to solve (within security as well as without).