Agreed. It's a neat site, though! There has been some variation in weapon use in recent years, but I don't know if this site would have really helped in revealing those details.
There was that whole period last year where people discovered the SG and AUG were actually quite good, and then Valve nerfed them into the ground again.
Several years ago, the UMP was insanely accurate when tapping/bursting, and it was a great half buy and anti-eco gun. That got nerfed, too. The MP5 behaves somewhat similarly, but it's not really worth buying over the MP9 in a serious match.
There was a recent discovery with the Nova, where the first shot spray was found to be consistent, and you could hit headshots consistently from distance by aiming to the right of the head. That one's pretty fun, although the situations where you'd want that over a deagle seem niche.
I think the biggest missing with this site is that it's only comparing raw DPS/rate of fire numbers and not spread recovery. A big part of it is the "feel" of bursting/tapping guns while momentum cancelling, when in scenarios where you can't full spray.
eg. Clicking on the head with a P250 at medium range isn't super accurate, but if you manage to momentum cancel perfectly and trace, you actually have a pretty decent chance vs full armor. But I could also buy a five seven, which has better armor pen, accuracy, and sprays better.