Often the "location" of the property is shown on a map. A lot of the time, this is often quite inaccurate.
The cynical might observe that this often happens to suggest that the property is not immediately next to a train station/sewage works/night club etc.
I don't know why the bother - I am going to find out that the property is not actually in the much-more-desirable location 250 metres away when I go see it. I'll immediately see it is next to the crematorium or whatever and immediately nope-out. It just wastes everyone's time.
Meanwhile, if you use the opt-out link, it instantly shows at least the name, location, age, etc.
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.
How much lag depends on your area. MLS isn’t well coordinated.