You can overdose on vitamin D and it can have significant side effects.
More or less anything that can have a positive effect on your health can have a negative effect if done wrong. If something has no possible negative effects it probably doesn’t do anything at all.
You can overdose on water but we still tell folks to drink several glasses a day, because most people don't get enough. That a tiny few are sensitive or go nuts with it shouldn't stop helping everyone else.
More or less anything that can have a positive effect on your health can have a negative effect if done wrong. If something has no possible negative effects it probably doesn’t do anything at all.