The thing is, it takes a conspiracy within the
Wikipedia's rank and
file to bias an article significantly over a long period; otherwise
normal editing and then RFCs and so forth will tend sort it out.
If it remains sufficiently inaccurate then the target will kick up a
big fuss; initially within the Wikipedia, and then other places like
Wikipedia Review and eventually in the press. The more people that
look at the bias, the less sustainable the position of the conspiracy
becomes.
Firms, organizations, or even individuals with PR budgets in the
millions, or passionate, but sane, supporters can and do much better than
that.
Fred