The lack of accuracy is the main issue. The information they have got wrong is the information you have shared, so a pretty low accuracy rate so far.
Their transfer valuations of players is so inaccurate and fanciful that even Fox News would blush.
Quoting Transfermarkt as a source of truth is crazy, but I see so many people doing it and it reinforces my belief in the need for the modern schooling curriculum to include teaching young people how to properly assess and evaluate a source and how to know what's useful and what spectacularly...