Infraction due to replying to a sales thread

OK,

Here is the deal. Somebody creates a WTB thread request for post here or PM me domains.
Now I can understand if the buyer himself bumps its thread by posting PMs replied or All PM sent type of messages but why a possible seller should get an infraction if he/her is PMing the thread owner with domain names and just reply to the thread indicating the same. A typical example is here

http://forums.digitalpoint.com/showthread.php?p=4123380#post4123380

Why should I get an infraction just because I replied "PM sent". Isn't just another way to signal the buyer he should check his/her PM inbox. I know it is not incredibly useful as many times buyer might be monitoring his/her inbox but I see DP member doing it all the time. In fact on the same thread many members have done the same. First Is this really an issue, Second, If yes, Is everybody on this thread have got an infraction or I am only scapegoat here

 

PM sent posts are considered infractions.

http://forums.digitalpoint.com/showthread.php?t=380173

 

Because that's a pointless post. You sent the PM and the recipient will get it. The rest of the forum doesn't care.