Comment by alecco

Mostly agree, but you have to be very strict with the DB architecture. Have very reasonable schema. Punish long running queries. If some dev group starts hammering the DB cut them off early on, don't let them get away with it and then refuse to fix their query design.

The biggest nemesis of big DB approach are dev teams who don't care about the impact of their queries.

Also move all the read-only stuff that can be a few minutes behind to a separate (smaller) server with custom views updated in batches (e.g. product listings). And run analytics out of peak hours and if possible in a separate server.