I expect it's the same reason that the quality of discourse on the internet as a whole, including the English Wiki, has really quite deteriorated. On the Chinese Wiki there's a tremendous intellectual barrier to entry - being able to read/write Chinese. This is not to say that China (as the largest source of people able to read/write Chinese) is not full of 'less academically inclined' individuals, exactly as any other nation, but the percent of those individuals that are in any way involved with Wiki is going to be extremely close to 0.

The entire internet itself used to have a similar barrier to entry in that it wasn't something that 'normal' people 'did.' And so you had a relatively small group of generally 'more academically inclined' individuals mostly just engaging with one another. But as you opened the flood gates the 'newcomers' gradually became the majority and the internet was completely reshaped in their image. So compare, for instance, old newsgroup archives to e.g. Twitter or Facebook. Makes it quite easy to lose faith in society. In my case it simply led to me tossing aside any notion of tabula rasa.

But the point of this is that I don't think individuals who are 'more academically inclined' are the sort to sit around wasting hours, days, years edit warring and effectively trolling one another. They can accept different views, values, and also correct themselves when they discover they had a poorly formulated view. Wikipedia entered the game early enough that the internet hadn't gone completely to the 'less academically inclined', and so it had some time to grow. In today's environment Wiki, from scratch, would be simply impossible. By contrast, the Chinese Wiki gets to party like its 1992.

https://en.wikipedia.org/wiki/Eternal_September