Just subscribed a short time ago and didn't have the same experience. I started following some interesting people, from my point of view, and I immediately got followers.

I suspect that some people follow new subscribers with similar interests so that they follow back expecting the new subscriber to see who they are.

The other thing I did was to tweet a private message to some known person who answered me. So this might have caught some attention too if it was seen by others. Since one has to follow both people involved in a "private" communication to see the exchange, this could motivate people to follow me.