Why do all MLS sites act like only realtors can use the mls and that the mls is a realtor only tool?

I was searching through the internet looking for info on the MLS. Turns out that MLS is not trademarked. Anyway I compared a few MLS sites. www.landandfarm.com www.lbar.com and a new one www.ourtownmls.com As a coder I found that only one MLS of these three was fully search engine friendly. Ourtownmls.com was fully friendly and didn't encode the listing which made it google and yahoo friendly so would I be better to list there and let yahoo and google drive hits to me or not? Should I rely on a sites current traffic to sell my home?