To be honest I have been guilty of that myself. The standards Van Dijk has set are so high and far beyond anyone else that people do go out of their way to "humanise" him where-ever possible. The fact is that, even with a few mistakes in him, he is by far the best centre back in the Premier League and would walk into any every top six defence and every defence in every top side in Europe.
Perhaps the best way to deal with the naysayers is to ask how many of them would have Van Dijk in their team. The answer is every one of them.
Yes, people tend to do that with unique players, like Messi, CR7, and now Van Dijk. Basically looking for any little mistake they do or anything not perfect to pick at and try to bring them down. With Van Dijk its even worse because of the team he plays for and the form we are in right now.
Beckenbauer, Maldini, Baresi, Nesta etc are the kind of defenders people mention when they talk about the GOAT defender. Now, they all made mistakes on their playing career, they all conceded goals, they all mistimed tackles or fell on their asses or even scored own goals, plenty of them. Thats just football, even the best of the best can have bad games.
Now Vidic and Terry are the ones that are compared to Van Dijk the most, and i could find you dozens of goals where both of them completely fuked up and were the main cause their teams lost or conceded.
With those standards, pretty much every player in history is "not that good".