It sounds like you believe that those medicines work well enough in all cases.
You only have to track the share prices of the pharmaceutical companies,after a press release of a new drug, to know that it is all to do with making big money.
As for doctors, how would they know.
"Take these tablets.If they don't work then we will try something else"!
Reports say that many who are suffering from Alzheimer's and showing better health may be in a remission stage which has got very little,if any, to do with the new drugs.
Therefore,let's not waste good money on plastic drugs just because of false hopes.