As true in 1888 as now, Froude: "Each age would do better if it studied its own faults and endeavoured to mend them, instead of comparing itself with others to its own advantage."

Those that ignore history are doomed to repeat it.

We saw it with tobacco/lead/etc, so it's only natural/right to apply that experience to other things. Theorizing that sugar/THC could also fall into the same model is not wasting of anyone's time. If evidence is found that it is bad, then good can come from that knowledge. If evidence is found that it is not bad, then party on Wayne. But the studies should be conducted. Let's look forward to having actual knowledge rather than just blindly carrying on in the dark with no flashlight to guide.