I can understand using blinking rear red lights or blinking headlights for daytime use. My brain associates a blinking light to emergency vehicles, begin to up your awareness and take caution like in a construction zone, and be aware of possible danger ahead. We see solid red and white light a thousand times during the day and night we subconsciously ignore 99% of them. We do notice something like a blinking vehicle turn signal and that ups our attention to be prepare ourselves to take possible action (change lanes, slow down, stop, or do nothing and be A-OK).
I ride with a blinking rear red light day or night when sharing the road with vehicles. I use a blinking headlight if sharing the road with vehicles during the day (solid light at night). Blinking white light does come in handy when single track riding in heavy woods.