It depends.

If you are missing milestones that need to be accomplished that are highly critical to compliance and basically keeping the customer/patient safe, then I would be able to accept missing it.
These are the type of situations that can easy be explained and accepted. Therefore, I agree with your statement.

If you are missing milestones that aren’t as business critical and aren’t as difficult to accomplish, then there is something clearly wrong with possibly the plan or the team. From my experience, missing milestones that aren’t as business critical demonstrates to me that the project may not have as high priority as I think it should have compared to what other people think.