True but, be aware that those 50 people did everything including the servers, the operations, the BI, oh and also maintained clients for like 8 different mobile platforms including ultra constrained ones like j2me and blackberry. If you look just at the iOS client, 5 people at WhatsApp on it would probably be a bit too high.
The issue here is only partly inherent complexity of the feature set. The real problem Facebook had is one I don't see discussed in either the blog post or this thread, which was organizational. The way they structured their mobile apps was as a huge shared codebase with many disparate teams just checking code into it whenever they wanted. To the extent there was any architectural planning at all it came from some small shared library teams who were in no position, managerially, to enforce their will on the others. The blog post makes clear that a huge portion of their problem was multiple teams inventing their own ways of doing things and creating stuff that want necessary, along with a lot of pointless duplication because there was so little coordination and thus so little code reuse.
The new app doesn't sound like anything special design wise, and that's the point: for the first time they've done things more conventionally. They now have someone who can dictate to every feature team "thou shalt use sqlite with these schemas" and other rules.
The issue here is only partly inherent complexity of the feature set. The real problem Facebook had is one I don't see discussed in either the blog post or this thread, which was organizational. The way they structured their mobile apps was as a huge shared codebase with many disparate teams just checking code into it whenever they wanted. To the extent there was any architectural planning at all it came from some small shared library teams who were in no position, managerially, to enforce their will on the others. The blog post makes clear that a huge portion of their problem was multiple teams inventing their own ways of doing things and creating stuff that want necessary, along with a lot of pointless duplication because there was so little coordination and thus so little code reuse.
The new app doesn't sound like anything special design wise, and that's the point: for the first time they've done things more conventionally. They now have someone who can dictate to every feature team "thou shalt use sqlite with these schemas" and other rules.