I think they meant that different people can give you different and conflicting advice.
Also, check out the Goomba fallacy. (The way you wrote "the advice was... now it is...")
There's not a single point in history where everyone on the planet advised any one thing at all, ever.
There has also never been a single point in history when everyone in the planet was over the age of 70, but there are also a lot more people who are over 70 now than 1000 years ago. I don't understand why you think that all fractions between 0 and 1 are equivalent.