This urban legend is really irritating, especially considering how many people repeat it mindlessly.
There. Was. Never. Ever. Any. Level. Without. Quest.
If you didn't found quests at lvl 45, it's because you didn't change zone, not because there was some imaginary "hole" in the leveling.
For a lvl 45 character, you had quests in Hinterlands, Tanaris, Feralas, Searing Gorge, Azshara, Blasted Lands, plus the tail end of STV, Badlands, Swamp of Sorrows and Dustwallow Marsh.
OH YEAH I TOTALLY SEE A LACK OF QUESTS HERE !
/facepalm
Considering the BS you said just above, you don't have a lot of credibility to such opinion.quests that awarded some 1% xp for traversing the whole world there and back, and so on. Classic leveling was a horrible experience, which was only acceptable because all the other MMOs were even worse.