i'll use an example to explain what I'm trying to say.
In Semi Devils and Demi Gods, Mu Rong Fu and Jiu Mo Zhi says in their opinions, the two most powerful martial arts they've ever seen are Yi Jing Jing and Six Meridian Swords (Liu Mai Shen Jian). As a result, skills like Tai Ji Quan are often overlooked.
A big emphasis on the word seen.
Many of the skills that come in later time periods such as Yi Tian Tu Long Ji are ones that people from earlier times, people like Mu Rong Fu, have never seen before. Lots of people say this skill is better than that because so and so said that skill is the best he's ever seen. But have you ever thought about it? That so and so has never seen skills that came after him, so how can you base arguments on that? Mu Rong Fu has never seen 9YingZJ before.
I've seen countless people back up their arguments like this, on both english and chinese threads.