Even now, when a landlord has a lot of available apartments they need to move or when the market is soft (for example during peak COVID), they’ll typically offer a “1 month OP.” Meaning the landlord pays the broker a 1 month’s rent fee, and the broker markets the apartment to renters as no fee. Even if the landlord just roles that into the rent, it’s a savings over the 12-15% fee standard today.
Also, landlords with larger buildings or geographic density are already figuring out that they can rent apartments cheaper with a few salaried leasing agents, instead of paying brokers. If more of them are forced to internalize the broker fee, more of them will figure that out.
Real estate agents don't even do that; a dedicated title company will take care of this aspect of it.
After doing a few real estate purchases with realtors, I've come to the conclusion that they're not really necessary as a buyer, unless you really need/want someone to hold your hand the whole way. The offer and purchase forms are standardized by the state realtor's association (technically they are not free to use, but you can find them online), and the seller will be responsible for filling out all the disclosure forms and whatnot, which you just have to sign that you acknowledge receipt.
As I said, the title company (often also the escrow company) will handle all the title-related stuff. Your mortgage lender will help you fill out the mortgage application, and either the title company or a notary hired by the mortgage lender will walk you through signing the final forms. In states (like NY) where you're required(?) to have an attorney when you're buying property, I feel like a realtor is even more superfluous.
On the seller side, I do believe realtors provide quite a bit more value. Whether or not it's enough to justify their commission is of course up for debate.
Regarding rentals, yeah... before buying I lived in 9 different rentals (upstate NY, SF bay area, SF), and at no point did I need any third party to help with it, even when several of these were before the prevalence of listings on the internet. Find listing, contact landlord and/or attend open house, submit application, sign lease, done. There were certainly some rentals I didn't end up getting due to high demand, but that's life.