There is always more than one single reason... but c'mon... acting like wolves are a small piece among many is little disingenuous. My family's been in the Gardiner area for 3 decades. We had bad droughts before (remember '88 fires?). We had high tag numbers for decades. We never had <5,000 elk in the Northern Yellowstone Herd until wolf populations went wild for 15 years. Unmanaged wolf populations have had a huge effect on the elk herds in those areas. No denying it.
Not denying wolves have an impact at all, but it's no where near conclusive that wolves were the biggest reason for the crash. They most certainly were additive, but so are grizz, black bears, lions. All of those critters have seen an increase, and so has development of winter range, loss of nutritional content in forage on public lands, too many tags, etc.
You can't look just at wolves. They may have accelerated the decline, but it was going to happen one way or another. There is a growing body of evidence to show that poor forage on some public lands is making a lot of ungulate species a lot more stressed (Absoroka Elk Ecology Project, Grand Teton Moose studies). Add two legged and four legged predators on top of that, and you have a situation ripe for a crash.
Should wolves be managed with a fairly heavy hand? You bet. There's nothing to indicate that we'll wipe them out even with the strategies that ID and MT have adopted. Are they the reason we can't grow elk? I don't buy it.