Most people SAY they would like a reply as to whether the other person is interested or not, but what they do NOT say, is that they plan to punish you if you are not interested. If you reply that you are simply not compatible, look out cuz you may be about to get a foul mouthed earful as well as a personal evaluation on whats wrong with you.

In other words, no reply is reply enough for some folks to handle.

If someone on the street were to pass me and say hello, I may nod back, say hello, or try not to make eye contact and keep on walkin. Lots of communication irl is non verbal.

Online, an empty profile communicates enough to some. So does an empty message. So does an empty reply. If the verbal communication you provide does not spark interest, why should someone invest time and energy, lead anyone on, and engage in shallow communication with them? Leading someone on is not polite. Everyone doesnt happen to have lots of time to kill online. That can be said of both sender and recipient.