Wikipedia is not continuing to grow because its policy is to delete articles whose subjects aren't covered in the mainstream press.<p>The mainstream press, on the other hand, is shrinking every month.<p>The current definition of notability is like Newtonian physics. It's useful, but must eventually be replaced by a more nuanced model.
What's the obsession with constant growth? Why does wikipedia need to keep growing? It's not going to disappear if its user base stops growing. People will still edit. People will still read it. It'll probably get better if it slows down a bit and starts to get real.
I think the reasons for the decay were already widely discussed everywhere:
1. there is a great amount of rules and guidelines which worsen the learning curve
2. quite often, articles are owned by "shepherds", who tend to rollback outsider contributions (because they have their own perfect vision in their heads); this contributes to despair of occasional contributors
3. because the topmost reasons to be a winner in a editor dispute are (a) persistence and (b) bone-headness
WP's a lot more daunting than it used to be for a newcomer. Every now and then I see an article where someone came along, dumped in a bunch of text (unique if not original), and ran away from merging it.<p>They could <i>really</i> use a hand-holding (offline?) editing environment. Stylistic expectations now are daunting for a noob - and their online help is, well, badly organized might be kind.