Democracy is a system in which people have a say in their own governance. If people lack input, they lack democracy.
Political parties by definition represent a particular interest and group, not the entirety. Parties select candidates who are then submitted to a general election. Significant numbers of people are not affiliated with any party. The election process, including media coverage, favors a two-party system and attempts to exclude other potential candidates.
Parties by their nature are exclusionary, meaning they keep out whatever does not align with their agenda. If two parties control government, and significant numbers of people are unaffiliated, then these people are unrepresented and therefore excluded from having input in their own governance.
If a system of government is a democracy, then all people have their interests represented. If an underclass persists within a society, its government can not be considered a democracy. A democracy is not a system in which a majority vote to exploit a minority, it is a system to ensure all voices are heard, no matter how small.
If one’s voice is not heard, then submitting to citizenship is of little value. The primary function of a democracy is to ensure that all voices have value, or else there is no liberty and justice for all. If all voices cannot be accounted for, then a population is too large to sustain democracy and must split until appropriate inclusion is reached.