99% of such people have un-realistic demands for their stuff, they don't want people to comment on it and for those who don't like to comment, at least they don't lose interest in the stuff when they see "call/PM" thing.
Like, I was browsing ads for a 8th gen civic, I came up to this very clean car, 2008 oriel Prosmatec only 33k driven and "call for price".
Before I dialed his number, I had a firm stance that this chacha is advertising for fun as the description read "I am in no hurry to sell the vehicle".
And that happened when he quoted 18.5 lakhs non negotiable for the vehicle. lol.
Ab maine 18.5 lakhs for 2008 model dekh kar ad open he nahi karna tha. Call for price dekh kar open kar lia.
Same goes for threads in here, one would simply close the browser window immediately after seeing such an out of the world demand.