Netflix Engineering team amazes me a lot. They literally took all the available apis, and build their own platform despite some of the features are already in the AWS offerings. I suppose they did it mainly because the native service isn't flexible and robust enough for their use cases. BTW, their opening positions are always prefixed with "senior" title but I guess that makes sense; Netflix builds pretty much everyt…
I asked that in an interview with Netflix, why they were building their own vs open source. The answer I got was "It doesn't work at the scale that Netflix operates" , not quite sure what that means but I didn't press him further.
The other thing is 'early optimization' when you know millions of users are going to use something, you have to build things right to begin with.