Artis are generally a complete and utter waste of shields in multiplayer. Most big battles only last 1-2 turns making the artis rather useless. Assuming you are not playing against total newbs or have certain map advantages, such as chokepoints. The only time I would actually consider building artis of any kind is if the enemy is sitting on mountains/hills and won't come down. What works great in SP does not necessary work great in MP!
Perhaps they are. I am not that experienced in multi.player.
My comment was made in the light of how bombers are nullified by bringing mobile sams with a stack. When a force has attacked us and tried to take our cities, we could counterattack and pick off their injured attackers with bombers and MA.
But since bombers are now nullified, I was thinking maybe a stack of arty could soften them up before picking them off. Not that I expect us to get many units to kill anyway....but it was just a thought.