Yes, I'm aware how Spreist works and the only thing that's hard about it is having a consistent connection and not getting fucked over by mechanics. Frost on the other hand lives and dies by if you can double Ice Lance consistently and on reaction to trinket procs, while not also munching procs to keep IV up as long as possible, preferably back around to IV if RNG permits while not fucking up mechanics. If you're just sitting there mashing what lights up, then yeah, Frost is easy as hell, but if you're actually optimizing it you aren't going to have as easy of a time.
I also didn't say anything about the classes performance or mechanical faults, so the rest of that has nothing to do with. Spriest isn't the only thing in the game that gets screwed by poor movement/boss mechanics screwing you over, unless you want to completely ignore a decent amount of the specs. Hell, I'd say that Frost DK and Demo have it worse, considering that Frost DK has nearly nothing to deal with having to get off the boss (woo you can cast HB for RP) while channeling BoS and Demo has Life Tap for slight movement and Demonwraith, which neither is going to help if you have to do nearly any mechanic in a timely manner, since you hemorrhage DPS the longer you aren't generating a decent amount of shards. At least Spriest gets VB for stutter movement, SW:D in execute and Dispersion.