Funny you should say that after today's FDA announcement. (Not taking any side here just interested in how we determine what is a consensus these days)
My go-to source for nutrition information is Understanding Nutrition by Whitney and Rolfes.
For some people choice of diet really does seem core to their identity. It’s literally all the OP ever posts about.
There may be a misconception that there is one single best diet for everyone, when in reality we people (over generations) evolve with our diets, and your best diet and my best diet may be completely different.
The problem with using science as a guide is that there are just too many variables and not enough time, data and money to isolate them all sufficiently.
However that is distinct from the idea that too much of something like refined sugar might be unhealthy for just about everyone. So science does have an important role to play, I just don't think it's advanced far enough to fully answer the question for everyone.