Sure, you can get that same deal (or better) for a mere five mana, rather than eight, but then you wouldn't be doing it every turn, turning your lands into 4/4 trampling, vigilant, indestructible threats, and you'd have to actually draw your spell, rather than just having it right there in the command zone
Just as Harmonize was much, much better than Concentrate, so too is Divination better in black than blue
So lets say youve gotten your hands on some gold or gems and want to get cards
With four mana, use three of that to untap Basalt Monolith
You need to be comfortable shipping your entire collection and waiting while they evaluate it
You do not discard to hand size during another player's turn, regardless of how many cards youre holding