Nope, that's not the case. I operate monerohash.com. I'm getting the entire peer list from the daemon (not just the ones that the daemon is connected to) and making a connection attempt to each one of them every hour, if it works, then it's added to the map and to the count.
The daemon returns two lists of peers, the white and the gray. I'm not sure what's the concept behind their names, as they have even been switched on this commit from May 28th. But the case is that the gray list seems to show the most recent and working nodes (hence I would call it "white"), and the other one seems to accumulate all the other peers that have ever been seen.
Right now the node I'm using for this (which is pretty up to date with master, and is not the one I'm using for the pool - that one is on latest stable release) has 788 peers in the gray list and 4996 on the white. From those on the white list there are only 2 or 3 that may be accepting connections on the port specified, but I'm not checking that list because to me it seemed like a waste of work to make ~5k connection attempts every hour to only get 2 or 3 working, which I'm not even sure they are monero nodes, as that list goes back as peers seen for the last time 390 days ago. So I'm checking only the peers on the gray list.