if it were just an object, it makes more sense that the seller does the leg work. they know the object, the market, etc. they're the expert.

why does a buyer need a expert on all the objects out there?

I know there's technical examinations like a home inspection that the buyer would have done, but if you're just talking about navigating the property and legal docs, seems like the buyer isn't going to need an agent to do that other than once to accept the price.