That is not a character flaw. It is arithmetic. An agency paid on ad spend has no reason to recommend working the practice's own dormant patient records, which has no media cost at all. No reason to recommend slowing down acquisition until the foundation is set. No reason to recommend anything that reduces the budget they are paid to manage.
Nearly everyone selling dental marketing sells the same one thing: media buying with generic search work attached. The practice is offered a single model and told it is the right model for their practice. A claim nobody could make about every practice at once.
You bought what was on offer. That is not a failure of judgment. It is what happens when an entire category sells one thing.