I understand. We all know what we know. Some people simply aren't old enough to remember Yngwie J. Malmsteen's Rising Force's first releases. Having said that, Yngwie might be the last guitar "hero" that truly changed the way guitar was played. He more or less created a sub-genre of metal, called neo-classical. It didn't exist before him. Without Yngwie, we may very well not have Symphony X and countless other bands.
The tenure with Yngwie is far from Jeff's only accomplishment, as he also sang for Journey, Talisman etc. but I stress his tenure with Yngwie simply because of the impact that band had on metal music. It is truly significant.