Why? The creaminess of a moisturiser can cause makeup to thin out if the moisturiser hasn’t had enough time to soak into the skin. This can result in blotchiness and ultimately limit the amount of coverage your foundation can offer throughout the day.
A better way: Wait 60 seconds, until the moisturiser is absorbed. Or, if you’re short on time, blot your face with a tissue after moisturising, then apply foundation.