Or the OP is looking at unimproved land/lots which don't have addresses. I'm currently looking at properties for a future vacation home and at least here the electric company assigns addresses--so if the lot doesn't have electrical service it won't have a real street address. You're lucky if the realtor lists the tax ID so you can look it up in the county database.
But as another poster pointed out, it costs everybody time when you need to make an appointment and then at first sight you see that this will not work out.
Edit:
With detached houses the obfuscation is harder/less valuable, but ideally I'd rather not have images and price and exact location of my property be linked online essentially forever.
Price is one thing, but internal layout and floorplan coupled with exact address is ropey.
Don't do that, it's incredibly stupid.