I've heard this from many engineers over the years.
But what I've often found is that they were never involved in the decision making process and so aren't aware of all of the business requirements. Once they are made aware usually they agree with the choice.
Common example being the business requirement to have high availability.
It is even the simplest things that are ignored such as:
- what happens to your db query when you have 1 million records?
- what happens when the cache goes away?
- do you even use a cache?
- why are you treating your cache as a DB?
- can we run 2 copies of your service?
- can your service scale up and down?
- does your service have state?