As veekie has said, if one looks at WotC publications that SKR had a hand in, one will relatively quickly notice a theme.
I went ahead and checked out what publications he co-wrote that I could find:
-Forgotten Realms Campaign Setting, introducing mainstays such as the 3.0 Hathran, Red Wizard, and Archmage.
-Magic of Faerun, with the 3.0 Incantatrix, Mage Killer (a full casting PrC requiring 4th level spells), and Spelldancer, as well as a slew of spells.
-Savage Species, without much in the way of notable caster PrCs, but a few later staple spells such as Girallon Arms + Fuse Arms, Maw of Chaos, and Major/Superior Resistance.
-Ghostwalk, with a few mostly non-notable spells.
-Living Greyhawk Gazetteer, which I don't have.
He's probably co-authored other things too, but these are the ones I could find by looking and checking his Wikipedia page. The sample size is small and correlation doesn't necessary imply causation, but it does provide ample grounds for suspicion.