> The effect size for antidepressants is 0.4

What the article states, then fails to take into account, is that is the mean effect size, and there is huge variation.

Anti-depressants are notorious for producing different effects for different people.

What that high variance means in practice, is for any anti-depressant, the people who get good results are getting a much higher effect than 0.4. And the other people move on to try something else.

So to keep comparing 0.4 directly to the effect of Vitamin D and Omega-3 directly is very misleading.