Sure, it's only a few minutes... ...if you're making a relatively small change to a non-mission-critical, non-distributed system that can be taken offline brie

Sure, it's only a few minutes... ...if you're making a relatively small change to a non-mission-critical, non-distributed system that can be taken offline briefly while you migrate; then you can just shut everything down, migrate, roll new versions, and start up again. If you need to keep everything running while you do a gradual rollout across thousands of DBs, this gets more complicated very quickly - and that's not even taking into account more complex migrations that involve more than just "add / remove this column". You're definitely right, however, to point out that implicit schemas don't make this better: you have all the same problems, but with less documentation / validation helping you not screw things up. It's also a good point that many businesses / applications never reach this latter stage where migrations become much, much more complex; when you can get away with the former approach, you definitely should.