One reason is just to remove as much possible contact as possible. The list is long of silly overkill rules like coming in contact with a positive case means 10-14 days quarantined. The insane part of this one is how "contact" is decided. That definition varies depending on the business or institution issuing the edict. For example: Quarantine of a 22 year old because he was eating a meal in the same room as a positive case who never came within 100 feet of him. Seriously, the entire room employed by a certain group was required to hunker down for 14 days. No testing or retest applied to that decision. That's a brilliant decision right?
Regarding Nursing Homes...The "big brother" desire is to keep the positivity rate above 5%. Why 5%? Because this is our governor's line in the sand. More rules apply, like not having a positive case in the home for 14 days prior. FYI, the rate in Ouachita parish is currently 7.7% according to CDC. Believe this if you choose. At this rate, it will be months before any home in Ouachita Parish can allow visits.
Why? Simply because they can. Keeping things abnormal is the new normal.
Meanwhile, hospitals basically do what they want. Doctor offices are the same. Meaningless taking temps is the only check the perform.