With the power of the internet, we are able to do many things from anywhere in the world. For instance, I can get a contract signed in my bathing suit sitting on the beach in Cancun. (Sorry for the visual there!) That's good for my buyers and sellers because my availability and ability to continue moving forward with purchases is increased.
On the flip side, in real estate, you can also be an agent in California and offer FSBO (For Sale By Owner) listers in Henderson a package where you put their home on Realtor.com and give it an MLS number. The advantage to a home seller is that you pay a smaller fee for the agent to put your home on Realtor.com. The disadvantage is that 79% of people find their home through a real estate agent according to the National Association of Realtors. Realtors look for homes for potential buyers in their local MLS, supporting local agents with listings and giving their buyers a large variety of listings with one search. If your home isn't in the local MLS, you're missing a big chunk of the market as a seller.
Also, you're still doing all the marketing for your home as well as all the legal legwork that an agent could be doing for you. When you use a REALTOR, you get someone who knows the in's and out's of the market, can deal with the buyer or buyer's agent for you, will deal with all of the showing and inquiry traffic, pays for the signs for your yard and all the advertising, knows what to ask of buyers and mortgage companies, knows how to keep the transaction moving along smoothly, and deflects much of the legal ramifications off you onto themselves as a licensed professional. That's worth something. I've heard people say, "I'll never buy or sell without using an agent." These have been folks who have done it that way before and know the headaches it can cause.
Selling your home can be an emotional experience already. Throw in some buyers who want to buy only if you throw in your wedding portrait over the mantle or leave the grandfather clock in the hallway, and it can turn into an even more personal battle. Why should you deal with negotiating all of this? Trust a good agent to do this for you and act as a mediator in this transaction.