I've read many posts recommending NOT to take an AI unless necessary. This seems to be good advice. Why take any medication unless is it necessary.

It seems many knowledgeable members have at various times warned against taking them. This has come up so often, I started to wonder. Other than the above explanation, what harm would taking an AI do? I've looked up the "side effects" of the AI I take - anastrozole. Other than the various innocuous side effects you can find on the label of practically any medication, there seems to be no long term side effects. Can someone tell us why taking an AI is not advisable?