Yep. I edited my original post because I realized you weren't talking about parking. I don't see anything unsavoury about Sedo asking you to point your domains to their servers in order to verify ownership. It's part of their method of doing business. So if you want to list at Sedo. That's what you gotta do.
I'm not defending any practice. I'm just stating that many registrars are doing this. I'd say that maybe more than 50% of my whois lookups look in some way like your example. Maybe as much as 80% (gut feeling). GoDaddy, eNom, NetSol (the big three) all do this. So. It looks like this is becoming the norm. If there is something wrong with what they are doing, then ICANN should step in and prevent it.