Not sure how this is cherry picking data.
It is cherry picking because you obviously searched for some sort of data that would make Federer look good without discussing the context.
There are only a handful of grass court tournaments each year, so very few people would be able to win 10 tournaments on the surface in their careers. Since Federer is one of these people, you can combine his 10 grass court titles with whatever you want and say that Federer is one of the only players to achieve that.
Federer is also likely one of the only players to have won 10 grass court titles and also won the AO without dropping a set...a great feat, but so what? You could easily cherry pick data and make anyone look good. Nadal is the only player to win 8 FO and also win the Olympics...is that an underrated record or is it cherry picking data?
If there was only a handful of clay court tournaments each year and many grass court events, Nadal would likely have won at least 10 on all 3 surfaces while Federer likely never would have come close to 10 wins on clay. In such a situation, Federer likely would have had a better overall career and Nadal a worse one, but Nadal would have been the one to win 10 titles on 3 surfaces and not Federer.
Do you see now how this is a useless record?