Law firms don't grow current clients because they lack intelligence about problems that drive demand, despite having the means to obtain it.
Marketing (lead-generation) cannot work without Sales (lead-conversion). Investing in one without the other guarantees expensive failure.
Good news: When it comes to rainmaking, lawyers are part-time rainmaking apprentices competing against other part-time rainmaking apprentices.
Online lawyer networks can bring you leads, but not clients. You have to convert leads to clients yourself, and you'll need sales skills to do that.
Lawyers need to escape two artificial constraints: geography; and the narrow economic and intellectual confines of the Law Department.