You don't believe in them, for yourself or others, and you've been trained well enough to couch your disbelief (eg "great if this sort of stuff helps") so as to avoid someone directly addressing your disbelief in them. Yeah there are side effects, but it's a personal choice. No one's going to force you to take them if you don't want them, but for people that find them useful, going around telling everybody that they're over prescribed and have side effects doesn't help people who would benefit from them get access to them.

> just get a diagnosis" line utterly inadequate

There's an entire industry with licensing boards and factories and regulations. How much more money do you want spent on the problem in order to form an adequate response, and what would that look like to you?