I've had a similar experience at a smaller scale with kafka and something of a CQRS architecture. I can vouch that at least 30% of development cost went into t

I've had a similar experience at a smaller scale with kafka and something of a CQRS architecture. I can vouch that at least 30% of development cost went into things that are otherwise very trivial. The risks of defining the wrong domain boundaries early on has culminating costs and besides specific use cases the benefits are not outweighed by the disadvantages. Even things such as business intelligence need to have knowledge of events and how they reduce to comprehensible state. For a startup this is can turn into a disaster of dealing with technology instead of focusing on solving problems. Lastly, GDPR really changes things when you need to be able to anonymise or delete data. It doesn't play too well with the event sourcing model.