....... ok then
How quickly can one build and how quickly can it scale ? - Speed is the name of the game - is it not this rule which holds true when building things on internet.
Or else, most of top internet apps are just going to be php,rails,node web-apps
One of the reasons that facebook succeeded in the early days of social was because it was so stable and well built. Their major competitor in the early days MySpace was a notorious frankenstein's monster of different codebases that regularly went down and broke parts of the site.
The chasm that separates web site and web application is wide facebook has always been a very advanced web application. I have spent a good portion of my career building decent scale (not facebook scale) web applications.
Several years ago I hired a data engineer who's primary experience had been in building custom data sets for BI organizations in big companies. He happened to drop in on an early planning meeting for an RFP we were completing and heard what we were proposing the MVP cost to build out an internal application for a company would be. Shocked he asked the room "why would someone pay us this much to build an overblown website". Two years into the project he gave our wider team a presentation on his role in the project the architectural complexities and places the team had innovated on the last slide of the deck he wrote "Closing Remarks: We should have asked for twice as much to build something this complicated"
1. What works really, really well is pairing people with deep domain knowledge and some programming ability with those who just have great programming ability.
Don't do that.
Most companies go with the mode don't hire unless the candidate is a great fit, because they don't want to bear the cost of a mistake. I have failed a decent number of interviews, some on technical ground, some on personal ground. I still think I am not a bad programmer, despite the failed interviews.
Like you I also have doubts about my abilities despite 12 years of work history in the Valley. Impostor syndrome.
Realize that most people are not as smart as Zuckerberg, and that they don't have to be. Don't use geniuses as a measuring stick of yourself.
The most important question is whether you like coding. If you do, pursue it. Whatever deficiencies you have, you will mend as you get more experienced.