Not a fan of the practice. But, I remember the same argument against
Craigslist's ads. Craiglists did shut them down, and the ads moved to
Backpage. I would argue that having the known "hub" for such activities
at least gives Law Enforcement a tool to help catch it. It isn't like it
is called the Oldest Profession in the World and it won't go somewhere else
to another site.
It's all about money. Shut off the source of income and add fines and
penalties until they do away with the ads. There is no point in
appealing to their conscience. If they had any conscience they never would have
allowed this type of advertising to begin with.