Anything you can do online is worth doing if you'd still want to do it even if you weren't manipulated into spending time with it.
As it is the net is a
big slot machine (look in the section headed "hijack #2").
The real problem isn't that corporations are directly manipulating
you, though (they are, but so has the advertising industry since its inception). Instead, the problem is that most online content only comes to you
indirectly, through other people. The
real problem is the inherent uncertainty of just who, when, and on what site you are going to benefit of online content being spread by other people.
See, the problem is, that the answer to that question is that you just don't know. And can't ever know for sure. People are opaque, non-deterministic processes. The only way to cope with this inherent uncertainty about who, when, and where you are going to run into somebody who provides something useful to you is by building up representations of the media as presented to you.
On some level, people
want to be constantly distracted, and will even pay money for it. But at the same time, if the web hadn't been co-opted for corporate profit, computers and networks could
easily have simply been all about doing research and representing information, and this fundamental non-determinism that that exists in people could be mitigated if we were all using our personal computing to build up representations that manage it and hone in our attention on what
we care about (rather than some external entity optimizing what you see in order to simply maximizes your online activity).
Corporations seek to do the opposite of this, though. We have a giant slot machine, because it's actually by
increasing the amount of uncertainty that we are forced to sift through
more media, which builds up networks of online media circulation from the bottom up from people with the smallest attention spans determining the criteria for what
you should be seeing, no matter how sophisticated the topic.
So it's not that you need to spend less time online. It's that corporations shouldn't have hidden the information you wanted all along under a mountain of distractions. It's the other people that are the problem, that lazy chunk of the population who don't see anything wrong with entertainment substituting thought, that corporations are harnessing in order to deliberately mix together distraction with quality content.
It's the same reason publishers often make the table of contents hard to find, or omit page numbers. You are deliberately being made to sift through a bunch of things you didn't care about. You are
paying for the content you consume by sacrificing your own psychological health, because you do a better job of helping grow the network if you respond positively to distraction, i.e., are psychologically damaged.