Eh, the technology stack they discuss is directly accessible, though.
I read this as an advertisement, meaning if everything it working well you don't need to manage the database. Which is probably how it works 99% of the time in fairness.
The circumstances are immaterial; if the creators of a system are blasé enough to imagine you’ll neither need nor want to manage or query the underlying data storage, then they’re telegraphing naiveté and inexperience. Capacity, throughput, latency, consistency concerns exist in any nontrivial system and the pointy end/bottleneck of these is very often at the level of persistence. Auth services can add privacy and integrity to that pile. And so on. Consequently, glossing over it with a handwave is a bright red flag.
To me this statement read very differently. I read it as saying that the amount of state is small and portable enough that I wouldn’t have to worry about scalability issues or be married to a particular database product. I think the original complaint about it is overly critical and nit picking.