It was found that drivers unconsciously filtered out a single small light moving like a bicycle does (weaving back and forth slowly, often towards the edge of the driveable area). Flashing lights are somewhat annoying but much safer for cyclists.
Both a bright solid light and a much dimmer strobe provide all of the benefits with none of the down sides.
A continuous light at least gets perceived as a path through image space. Strobes on the other hand can easily fail at getting perceived as belonging to the same unit of light source when there are many other illuminated dots (xmas crap! rain droplets!)