Because there are people that directly control millions of votes in companies and no similar structures in a democracy.
The number of shares is the wrong number to reason about, it's the percentage of control that is interesting. If an individual has 51% (or more) control, the comparison to a democracy is obviously nonsense.
(I used 1000 shares because it feels like a big number of shares but is still an utterly insignificant portion of Ford, which has a bit less than 4 billion shares)
They should do whatever they want to do. My point is that when a situation is futile, they should recognize that it is futile. A protest vote for a board member of a company strikes me as one of the more pointless ways to exercise a right to process.
In democracy, you can spend money on a PR campaign to sway many millions of votes your way.
And as another commenter noted, once a candidate is in place, lobbyists can pay to get proper legislation passed.
Finally, voting is rigged in any place where voting computers are installed, which appears to be a lot of places. Again, for the right money, you can completely change the course of an election.
Then why don't we ask the same in a democracy?