The architecture in TFA is fine, and sounds preferable to microservices for most use cases.

I am worried by the talk of 10k daily users and a peak of 1000TPS being too much premature optimisation. Those numbers are quite low. You should know your expected traffic patterns, add a margin of error, and stress test your system to make sure it can handle the traffic.

I disagree that self-inflicted architectural issues and personnel issues are different.