Even people who openly aim to violently overthrow the government and abolish elections?
If they're an electoral majority then you already have a problem.
But the point is they're less likely to get there if they're part of the power structure.
A presumed but frequently not mentioned component of democracy is the peaceful transition of power once a decision is made.
Yes, why not? If they are a minority, then there's no issue. If they are a majority (or close to it), then perhaps they have a point.