TL;DR -- The article is of questionable epistemic reliability.
I had not, but since it was counterintuitive to me I took a look at the article. For something that doesn't have a good first principles explanation, I tend to think it should provide some clear evidence for me to change my priors. I did not leave the article with this feeling. When reading this article, these posts came to mind ( https://www.lesswrong.com/s/GSqFqc646rsRd2oyz/p/34XxbRFe54FycoCDw and https://www.lesswrong.com/posts/SFZoEBpLo9frSJGkc/rationalization ). As a vegan/vegetarian, it could be me doing the rationalization, but here are the aspects of the article which made me skeptical of the results.
The initial intention of the data was not to look at this problem. The data was originally collected to look at the risk factors and progression of diabetes, cardiovascular disease and other chronic noncommunicable disease. This means the study was not designed to really determine the answer to the question of depressive episodes and a meatless diet. Before looking at the results of a study, you should agree that the answer will be reliable given the study design. This study would not fit that criterion for me.
This is a study from Brazil. Generalizability to yourself should take that into consideration. This study also includes active and retired employees of public institutions of higher education and research in six state capitals. This study found a meatless diet in only 0.6% of their population (only 82 patients of over 14k) when they mention at 2018 study reporting 14% of a studied population in Brazil as vegetarian. Of note, in Table 2, only 8.5% of the "do not consume meet" respondents self-reported a vegetarian diet/reduced meet intake which brings into question the validity of the results.
There was no overall difference in the CIS-R score between groups. There was only one statistically significant difference in depressive episodes and that was mild without somatic symptoms. Their crude model included 1.00 in their 95% confidence interval. They said that "In the present study, we found a lower intake of unprocessed/minimally processed foods and a higher intake of ultra-processed foods among those individuals who did not consume meat." Meatless diets had lower intake of overall calories. They also had lower overall intake of ultra-processed foods compared to those who eat meat (but not as a % of TEI which is how they made that claim). If, as a vegetarian, I eat 2000 calories and 500 of which were from girl scout cookies that would be 25% of my TEI (total energy intake). If the authors eat 3000 calories and 700 of which is girl scout cookies (23%), they would conclude that the vegetarian had a "lower intake of unprocessed/minimally processed foods and a higher intake of ultra-processed foods". That seems intellectually dishonest to me.
Ultimately, I do not find this article very convincing. I think one ought to require other better constructed studies to start to update their belief that meatless diets are associated with depressive episodes.
I hope you enjoy them like I did
A really simple example of what industry doesn't care about outcomes and pumps out product despite lack of evidence of effect and even potentially adds harm is the supplement industry. They dont care about brand reputation because they just change their name or bring another product to market eventually. If you take the FDA away you will have every major pharmaceutical just releasing garbage medications that barely improve life, yet increase cost and add side effects. They already try to do this with non-inferiority studies rather than coordinating studies that show improvement. Not to mention many currently available medications barely (and statistically suspect at times) show efficacy yet rake in serious money. This argument clearly is coming from someone outside of the medical industry with a limited understanding of mechanisms at work. It seems to be coming from someone on the early side of the Dunning-Kruger Curve.
Regarding surgery there are immediate outcomes and they are treating a specific problem so it is easy to measure. These are absent or limited with medications. If a surgeon is consistently not taking the gallbladder out from patients but telling them they did, this will be discovered quickly and typically the surgeons will either be sued into not practicing or be removed from the surgeon pool. The same goes for a surgeon who isnt safely putting an aortic valve in. First off, they typically dont get to the point of being able to operate on people if they are terrible. If they do, patients die. Then the surgeon is removed from pool of operating surgeons. Thats not the same for a medication that reduces the risk of heart attack by 50% from 1% to 0.5% over a 5 year period. Have you ever seen marketing from industry? Its terrible and not aligned with the truth. It is aligned with selling a product and if thats all they need to give to a doctor then you are going to get offered medications you dont want to take.
There are also methods of self-regulation by surgery departments, residency training programs, medical boards, state licensing agencies and professional associations. So, to say that surgery is not regulated is just misinformed at best. Your argument is just really empty. I understand what you wish to be the case, its just not realistic. Its the same argument that there is no need to regulate companies from dumping pollutants into the Hudson because they will avoid it due to reputation. Thats just not how real life works.