Basically you get rid of the quarterly reporting grind and it lets you focus on the business even if certain initiatives are going to depress shorter term results, but pay off over the long term.
Dell is a special case because it was the original founder who delisted the stock. Not some Bain Capital type firm that was just buying it to suck the marrow out of the bones before tossing it in the trash.
Basically you get rid of the quarterly reporting grind and it lets you focus on the business even if certain initiatives are going to depress shorter term results, but pay off over the long term.