> I mean you listed several database libraries, static analyzers, and a code optimizer.
Correct.
> Is it your suggestion that those kinds of applications do not require solid knowledge of a variety of different data structures and algorithms?
No -- precisely opposite.
Your response confused me quite a lot, but after some thought, I think I've realized how things have become mixed up. I took this for sarcasm:
> Which innovation of Facebook are you describing? Instagram, WhatsApp, or the stories?
Why did I take that for sarcasm? Because it is apparent to me that Instagram, WhatsApp and stories are not innovative. So I thought the main point of the poster I was replying to was to take a dig at Facebook. I didn't realize that we were in agreement about the importance of data structures and algorithms, but then I also didn't realize that we were still on that topic: my intention was purely to refute the [what I believed to be the implied] notion that nothing innovative was happening at Facebook.