I remember I was at Microsoft more than a decade ago now and at the time there was a lot of concern about search and how far Bing lagged behind Google in geospatial (maps). After some initial investment in the area I was at a presentation where one of the higher ups explained that they'd be abandoning their investment because Google Maps would inevitably fall behind crowdsourcing and OpenStreetMap. Just like Encarta…
The people doing many of these projects often want the short term kudos, upvotes, or research articles. They may iterate fast, and do all kinds of neat advancements, except in a month they'll move to the next "cool" project.
Unfortunately, with a lot of open source projects, they don't want to deal with the legalese, the customer specific integration, your annoying legacy system, the customer support and maintenance, or your weird plethora of high-risk data types (medical industry I'm looking at you)
Not sure what the Wikipedia reference is, since how many people use any form of encyclopedia other than crowdsourced Wikipedia?
However, to note, there are some examples of successful long term open source. Blender for example being a relatively strong competitor for 3D modeling (although Maya still tends to be industry dominant).