LinkedIn is a great networking tool no matter where you are in your career. You can make connections that wouldn't other otherwise. I know it sounds like a cliche answer, but it is true.
Sarah, who you enjoyed working with before she took a job in the next state (and who you wouldn't mind working with again)? She's not at the meetup - too far.
That guy who's become the software manager for a company that you're interested in? His daughter has a ballet recital, so he's not coming to the meetup.
But LinkedIn is always there.
Don't get me wrong, I don't use LinkedIn. It doesn't work for me - or perhaps, it's too much work for too little benefit for me. But if you're trying to connect with someone in particular, meetups aren't a very robust alternative.
I personally know plenty of past coworkers who I respect and would gladly recommend in a heartbeat. LinkedIn is the perfect way for them to see that I work at the company they want to work at, and gives them a frictionless way to send me a message despite us not being actual friends.
If you don't find enough value in that, then maybe LinkedIn isn't for you.