Reason #1: It's the law in Ontario to have a lawyer represent you. It's not a scam by lawyers to make business for themselves. The law of Ontario requires that every buyer and every seller of real estate be represented by their own lawyers (unless the area is remote, where one lawyer might be able to do both sides of the deal). It's true that lawyers aren’t required to be involved in every real estate transaction in a lot of other jurisdictions. But if you consider that real estate is likely the most expensive thing you'll ever buy in your life, unless you're really into rare luxury cars or mega yachts, then the fact that you'll be paying a fraction of a single percent of the purchase price in legal fees seems sensible if it protects your investment. Believe it or not, lawyer do stuff on a real estate deal beyond print out a lot of paper that you're required to sign.
Reason #2: There may be legal problems with the title to the property. Most people now hire home inspectors to check out their dream residence for fatal building flaws. Your lawyer is there to help minimize nasty surprises over fatal legal flaws. Like that there's a registered right of way for an oil pipeline through your backyard. Or that half the garage that comes with the property is actually located over the neighbour's lot line. Or that two liens for non-payment of large debts are registered against the property.
Reason #3: You need to borrow money to buy the property. Very few of us are able to pay cash for real estate, unless we're buying bare land or a really run down house in a very cheap location. But anyone lending you a large sum of money to buy a property is going to want to register a mortgage against the property to secure the debt. And placing a mortgage on a property requires a lawyer, in part to make sure there aren't other priority claims already registered against the property in which case your lender might not be willing to lend, or might only lend at a much higher rate of interest if it doesn't get first priority against the property.