Biggest thing stopping a true FSBO site from working is that it is considered illegal to advise in buying and selling property UNLESS you practice Law, are a Realtor, or it is your own property you are selling. You cannot fill out a legal purchase and sale agreement, nor can advise someone how to do it unless you are one of the three listed above.
Therefore, it is difficult to find the process available on a website or DIY...
If you advise, you are practicing real estate - if that rule is ever overturned, then it would be over for Realtors..
Frankly, I don't like realtors, mostly for ethical and reasons based on professional courtesy. My realtors rely on ME for referrals, not the other way around.
Good when you have connections.
rjp