Whilst fear & ignorance are probably behind some of the anti med thinking, the thing is that with a lot of ADs, the boffins still have only a rudimentary understanding of why the meds work for some & not others. Quite a few meds were originally designed to treat other things & their effacy for use with MI was a secondary, or accidental consideration.
It is also a little disconcerting when you think that you're taking something that essentially alters the way your mind works. However, in my case, the way it was working became untenable, so the meds were preferable.