I think Lanyrd's "tracking" feature solves this, because it shows which of your friends are interested in the conference right alongside those who are slated to attend and/or speak.
It goes some way of solving that issue yes. Ultimately though the problem of "few people registered" is poor sales, and to a degree marketing, by that individual conference.
There is a reason why conferences (as opposed to trade show events) heavily discount early-bird tickets. Cashflow and the ability to market more heavily. Lanyrd makes marketing easier, down to the organiser (and ticket agent) to make sales work well!
