It's so stupid, but definitely can be helpful professionally to maintain a profile there. Depends on your experience and what field you're in, of course, but recruiters seem to use it a fair amount.

Definitely don't use it for the garbage social media aspect (it's like some weird crowd-sourced Chicken Soup for the Soul shit??) However, I've been convinced of its utility after getting a new job through a recruiter there without even looking. The process was sooo easy compared to applying for jobs the traditional way. Icing on the cake was that it came with a 50% raise and was for a position I would never have applied for on my own but I love it. Maybe it was lightning in a bottle, but I figure doesn't hurt to keep up a page just in case another good opportunity comes along. If nothing else, the recruiters I hear from give me a sense of how hot the market is and what kind of jobs my profile is pinging me for in case I want to make tweaks.