Ideas like this have been tried several times, inclduing using online resources. They tend to have... underwhelming results, and if anything, it just leads to frustration by fans who feel that their contributions were not properly considered or 'weighted'.
Notably the warhammer franchise had a huge event a few years back based on a war between chaos and the empire in their setting. The result? The messia-like hero of the empire's armies was assasinated by a bunch of evil mutant rat dudes. Yyeah, that didn't go over so well.
Additionally, there's a lot of ill will towards 'metaplot' as an idea, in the fandom. Many games had some form of metaplot for instance in the owod era, but it was broadly seen as a way to railroad the players and override their contributions. Even in a system where player contributions were valued, the idea of various ongoing outcomes being asserted is fraught wiht peril.
It would take a very deft touch to manage such a system. . . not to mention, positive fans- and frankly wotc has a lot of people who bash it if given any excuse to do so.