I don't consider epidemiology to be bs or just hypothesis generating as do most scientists.
It finds subtle long term trends that are too impractical to find with other methods like RCTs. So if a lot of high quality epidemiology says saturated fats increase heart disease risk by 20-30% over decades then I will likely believe it. Just like it found a trend with smoking.
Why do you consider this epidemiology better quality than other epidemiology?
The same reason why any experiment can be better quality and well respected than others. You should look at a study's design, strengths, weaknesses etc and evaluate it.
Let me ask you one question back. Do you consider astronomy or evolution to be bullshit too because they are based on observation as well?