If you are curious on a proper source examining ideal protein intake, this link should give you plenty of reading.

Unfortunately there are a lot of incentives for various organizations and companies to put out literature in support of what makes them profit, not to mention many researchers who enter the field with a significant bias, conducting poorly controlled studies to provide evidence towards their biased opinion. Any summary articles on the internet, including ones from prestigious universities, should not be taken at face value when they do not cite their sources. Even when they do cite their sources, there's endless conflicting evidence out there because there are so many biased studies conducted by companies attempting to push their product (dairy industry is a good example of this), endless poorly controlled studies, endless studies based in science twenty years old and not accounting for more a more modern view of human health/biology and endless studies with other problems. A thorough review of the cited literature is often necessary to parse whether the source is tainted.