In reply to kireeti1192:
IMHO, the cookbook wording is a bit strong. The problem is when people rely on input functional coverage without following through on functional verification. For your example, it not enough to cover the fact that you applied reset to your RAM, but that the reset actually changed the contents of the RAM correctly.
I’ve seen many places where input coverage gets captured for sending different configurations to the DUT, but there is no test verifying that the DUT actually went into that mode. In some cases you have to look into the DUT (whitebox) to figure that out, but sometimes that is not possible.