This is partially correct and honestly if your consulting agency wasn't upfront about this they're overcharging the business either today or down the road when the business comes back needing more.

Good service is ones that solve the problem in a reasonable time. Great services accomplish the same as good service but understand that the code, company and even the pipeline will evolve and either the client will need to reinvest themselves or externally again. They will communicate this with the limitations to the client.

There are only two types of clients I've seen more inline with the original statement, declining or flat company and both are only in the maintenance do not touch phase.