Well, why are we so confident that we have the right answers to this deeply complicated nutrition stuff? I bet those doctors are equally confident, along with the vegetarians sure in their knowledge that red meats and butter are terribly unhealthy. And ofc there are studies that support each of these views.
Those doctors are contributing valuable input to the overall discussion, probably. If they're not right on all subjects that just leaves room for other people to come in and debunk their claims. Maybe unfortunate that people are affected by these untruths, but progress has always been slow. Doesn't mean we're not getting there.
If we're talking in terms of human health on a large scale, I don't think suggesting a limit to saturated fat is nearly as damaging as fast food chains, giant snack food companies and even normal restaurants. Seems kinda silly to be getting upset over these sorta things when there is a much bigger problem that goes largely unaddressed. A problem we can all agree on even lol.
About those specific claims they're making? I felt my healthiest when eating a high fat diet and would have no qualms with doing it again, but I'm still not 100% convinced that it's the best way to eat. Some new studies could come along and convince me that low fat high carb is somehow better. Or even that raw vegan is best. I bet if everyone followed the nutrition guidelines set out by their governments (USDA and such) we'd be much healthier on the whole than we are now.
I find it helpful to keep in mind that the people who disagree with us feel just as strongly about this stuff and have what they feel are solid reasons for believing what they do. If we listen to them politely instead of having a strong negative reaction, everyone is more likely to grow in their understanding.