Granted, the early turns dump could happen with dragon-oriented heroes, but it is much rarer than Vandaar/paladins/Finley growing their minions over and over again, turn after turn since turn 1- this is of course anecdotal, I have no numbers.
Rebanning the sphere will only solve druids’ starting deck, Elise still has the option of taking the (recently made) 1 mana priest weapon - so you would actually have to ban both. Which would make it like the 10th banned priest card overall.
20 mana on turn 3 is indeed an issue, but it is statistically a much bigger problem in early games than in later ones, since no matter how many empty buckets one chooses, it will be progressively harder and harder to draw Guff AND two (or both) weapons so early that it would allow you to have the 14-18 mana at turn 3. Plus, your hand would have to be from left to right EXACTLY: Twig > Guff > another up to 5 mana weapon, no cards in between (unless 1 mana or zero cost), and assuming you had goggles + 2mana/3mana at the start passives offered. Other combinations will of course happen, but only on later turns.
While your dragons ALWAYS cost -2, and your divine shields ALWAYS procc +2/+2, no matter how the cards look in your hand. That is the real issue.