Depends on your definition of slacker... The original article says "Getting air on a 10 foot tall ramp with a skateboard? Also cool." yet most people would describe a skateboarder as a slacker.
I think being around people that aren't necessarily "productive" is perfectly fine. It's being around people who do NOTHING that is bad but I find that if you are the kind of person who does things then you will find yourself around inactive people less and less over time.
Couch potatoes seem to attract one another and repel everyone else.
It does seem to be a fairly context-dependent term. A lot of people here are one kind: the kind of person who has enough time to accumulate thousands of posts on HN is, at least in some people's minds, a kind of slacker, the 2010s version of the 1990s posting-from-work Slashdotter. :)
It even takes a certain kind of slacking, in a sense, to read lots of random Wikipedia articles, keep up with current events, browse arXiv papers not directly on the topic of your current work, keep up with recent music, etc. Arguably reading a lot is not really slacking. But maybe keeping up with recent musical trends is? Seems all quite subjective, unless you literally are doing nothing.
I tend to see it more as different thought/work styles along several axes. For example, on a question of dabbling in side projects, for some people it'd be good advice to suggest laying off and concentrating more on one thing, while for others, encouraging a bunch of side projects is exactly the right advice. Some people need to do less random-walk reading, while maybe others need to do more...
I actually had the opposite situation growing up and it seemed to help me. I was certainly surrounded by slackers, with a few really motivated people sprinkled in-between. I'd say seeing mediocrity motivated me to differentiate myself and do some really cool things.
