I think the sample rate for counter is assumed to be by "a single
sample", and if you are incrementing or decrementing by values greater
than 1, and using a sample rate, it would confuse the server, which
basically takes the values it receives for a data point, and
multiplies them by the inverse of the sampling rate to estimate what
the "real" value was, before down sampling.
If you are doing this by values greater than/less than 1, that
calculation would be meaningless.
Sam