There is a reason why The Toronto Real Estate Board asks you to sign and acknowledge at least (4) four times that you understand who is representing you in a real estate transaction.  Particularly if you are the Buyer, they want you to understand that the Seller has a Realtor who is looking out for his/her best interests.  And, if you choose to buy a home directly from the Listing realtor, then, you will not have your own Realtor looking out for your best interests.  Which means, that the Listing Realtor will do his best to get the highest price possible for his Seller.  After all, that's where the loyalty is.  The Seller has his own representation.  If you are a Buyer, dealing directly with the Listing Realtor, you may be treated as a 'customer' and will not have the full scope of services available when you have your own Realtor looking out for your best interests.  

Many buyers believe, that if they deal directly with the Listing Agent that they will come out ahead.  They believe that they will save money because the Seller  will have just one commission to pay.  In reality, if there is any extra money, it's the Seller who will  benefit from the transaction.  The listing realtor is working and looking out for the Seller not the Buyer. Any 'savings' will be passed onto the Seller not the Buyer.  

If you are considering making a purchase directly from the Listing Realtor, you should  be aware that you may not have your best interests looked after.  You may over pay for the property and not have the best terms negotiated on your behalf.    Not having your own representation could cost you thousands of dollars.  Because it's not what you know, it's what you don't know that can hurt you.    Knowledge makes the difference.