He's not weak:
Yu Yu Hakusho 150 page 08 | One Manga
Yu Yu Hakusho 150 page 09 | One Manga
Ya... That's the shockwave of his punch destroying half a plateau :/
I'd like some proof that DBZ's earth is more durable than YYH's too... I don't see anything suggesting that.
Personally, I don't judge by size of explosions or how they power up, but intensity of the fights. That makes the most sense to me anyway...