Comment by TulliusCicero

It requires cooperating with domestic Chinese censorship and providing personal details/actions of users by default to the Chinese government to an extent that Western companies generally aren't okay with.

However, this is all a deflection, because blocking a company from operating as a business within China is not the same thing as banning them by blocking all access to their foreign websites/apps.

If China didn't want Wikipedia operating fully within China as a nonprofit, but you could still access foreign countries'/languages' Wikipedias, I wouldn't necessarily describe Wikipedia as "banned in China". I'd maybe describe it as a partial ban at most.