The full service Marriott where I am currently staying has not replaced or replenished the soap for my three day stay. It is definitely a property-to-property policy on doing this.

If you find the replaced soap wasteful, simply remove your used bar(s) of soap and wrap in plastic before housekeeping arrives. when they replenish the soap, just keep the new wrapped bars and continue to use your current bar. Take the wrapped bars home and donate to a homeless shelter.