Having access to your best spell whenever you want it, and getting a body as well, allows you to close out the game incidentally, as a side-effect of cementing your control over the game
This comes back to the True ConvictionTrue Conviction debate, and I think the answers pretty clear: unless youre playing 40 nonbasics with Alpha dual lands mixed in, the mana wont be good enough
That deck functioned a lot like a Flicker deck
We've all had our two lands tossed randomly, or our two best cards
In exchange it doesnt come into play prepared, so you still have to work for it first
Sol Ring and Arcane Signet aside, Talisman of Curiosity and Dimir Signet both help significantly