Stop talking about Stealth Rock. Stealth Rock is everywhere, case closed, even if it's not as common as it used to be (which I cannot confirm).
Arcanine is not a good user of AV. Here are some calculations:
-1 252+ Atk Huge Power Azumarill Waterfall vs. 4 HP / 0 Def Arcanine: 254-302 (78.8 - 93.7%) -- guaranteed 2HKO
So, after recoil or SR, that's a OHKO with intimidate.
252 SpA Life Orb Starmie Surf vs. 4 HP / 0 SpD Assault Vest Arcanine: 257-304 (79.8 - 94.4%) -- guaranteed 2HKO
Once again.
-1 252+ Atk Mold Breaker Excadrill Earthquake vs. 4 HP / 0 Def Arcanine: 296-350 (91.9 - 108.6%) -- 50% chance to OHKO
Not quite a OHKO, but again, with two recoil moves and a weakness to SR...
252 SpA Life Orb Greninja Hydro Pump vs. 4 HP / 0 SpD Assault Vest Arcanine: 320-377 (99.3 - 117%) -- 93.8% chance to OHKO
Again, here's the case of not quite a OHKO, but after rocks or recoil, it would be.
252 SpA Choice Specs Latios Surf vs. 4 HP / 0 SpD Assault Vest Arcanine: 238-280 (73.9 - 86.9%) -- guaranteed 2HKO
It cannot do anything back, either.
What I'm getting at here is that Arcanine is not a good user of AV because it obviously can't have recovery, but it instead can only take recoil damage. It's weak to stealth rock, too, making a lot of these calculations OHKOs (bear in mind also that intimidate is activated on all of these). It has intimidate, which gives it a physical defensive advantage, but does that mean the AV should be slapped on it to make a defensive monster?
Before posting about how good an AV user is, try testing it and finding some reasons as to why it is good.