Toto was actually made up some of the best studio musicians of the time who worked on numerous other recordings. Probably the most famous was their backing of Michael Jackson on his “Thriller” album which is one of the biggest selling albums of all time.
The first version of "Human Nature" was written and composed by Steve Porcaro of Toto.
Lukather also played guitar on “Beat It”, with Eddie Van Halen.
This is the funniest “solo” Lukather ever did.
https://www.youtube.com/watch?v=Q6PpCA7BV7E