Not responding to an initial email is (IMO) different from chatting with someone for a while and then going silent when they suggest meeting in real life.
Clearly, online dating was not for me which is why I stopped doing it. But I didn’t think it would make things any better to give that message. I haven’t done much internet dating but I’ve done a lot of IRL dating and if I barely know the person, I would prefer they just quit calling than that they tell me “hey, I’m making a conscious decision now to stop calling you because I’m just not that into you”. So that’s what I do.