No Showings on Multi-family Residences Until Contract Accepted

I am seeing more and more duplex, tri-plexes and four-plexes that have a notation in the multilist that showings are not allowed,until a contract is accepted.  So the seller expects a buyer to write on a property, which they have not even seen yet?  I find that very strange.  Granted the buyer can terminate the contract based on the inspection later, but that really seems like a waste of everyone's time.  Perhaps it works out well for the seller in that once the buyer is under contract, they have alot more emotional ties to that property, and even though inspection items crop up, they are more motivated to continue with the contract.  I suppose it depends on which end of the deal you are on.