Stevie is a genre all to herself.
Without her and Bob Welch Fleetwood Mac would still be a nothing but pretentious British band with no taste or execution.
However, the singers of The Who, Led Zeppelin, or The Rolling Stones are NOT in The Rock Hall as individuals despite most of them having meaningful catalogs of solo material. Daltrey and Plant and (to a lesser extent) Mick basically created the "golden god" frontman persona that miles of others have copied. But their solo material hasn't launched a thousand careers.
Please understand this isn't a fight with Stevie. It's a fight for principle.