Blizzard \ Frozen Orb inefficient?

Hi guys, maybe someone can shed light on this topic.

I know all or at least most hate the mix of Blizzard + Frozen Orb. Reason being, that Frozen Orb costs synergy points from Blizzard.

But what if that is not the case? If you get to lvl 20 Cold Mastery with 1 hard point that's already 115% reduction the Protector's Frost jewel and one rainbow Facet cold offer another 15% and an Infinity wielding Merc yet another 85%, which is above 200%.

Some may argue that the hard points would offer 19% more resist reduction when sundered. But even without, you have 5% base, 23% Cold Mastery, 17% Infinity, 15% jewel + facet so 60% reduction. The 19% more would only increase the damage by 33%.

For that you get two full synergized frozen orbs per Blizzard cast and your Ice Blast is 33% stronger, since Frozen Orb is a damge synergy.

When we assume 85% of the mobs being not cold immune and as such receive -200% and with the rest 15% also only 25% of the damage is missing, when in reality the Ice Blast and Frozen Orb usage probably even surpass the full Cold Mastery damage. I don't see the point why Blizzard \ Frozen Orb together shall be worse.

Thoughts welcome