In some college towns its not rare to have fractional leases where a student is only responsible for a specific share --but these are separate leases and not comon elsewhere and I doubt that is waht you have if a group of you rented a house..
In general, many a lease calls for the tenants to be jointly and separately liable for the whole deal
That means if 3 of the RMs drop the ball the 4th can be looked upon to pick up all the slack.
And it also means the LL can pick and chose which ones to chase for any shortages --he need not cut nice guys any slack and he can avoid chasing people who are hard to find and focus on the easy targets even if you think everyone or others need to be the targets.
The bottom line is its in YOUR best pocketbook interests to hammer your roommates and if necessary YOU sue your RM's for not paying their share of the rent or fixing their damages.
Absent any mistakes by LL, I predict LL wins this one and gets a judgement against at least you if your were served and anybody else who was served even if they are a no show and lets say it is for $1500 including costs etc---he is entitled to chase you for the entire $1500 --he need NOT cut you any slack as there is not real slack in the overall duty to pay.
If some of your RM's have departed to far away states that may leave you as the only viable target
Your beef is with your RM's--its up to you to go get it! .