In this case your landlord has two roles. The first role is as property manager/lettings agent for which he gets some money. You are probably right that it accounts for a small fraction of the total amount he receives. He can also hire someone else to do this role for a small amount. The second role is as the owner of the asset that is producing value. In this case the rental property is generating value by providing a place for you to live.
In my area it is much cheaper to rent than to buy (taking everything into account, moving costs, selling and buying costs, mortgage, maintenance, inflation, etc), so my landlord is subsidising my housing costs. So it is a win for me, and my landlord seems happy too, so a win for him.