(i) We can understand the necessity of political parties by imagining a situation without parties. Every candidate in the elections will be independent. So no one will be able to make any promises to the people about any major policy changes.
(ii) Elected representative will be accountable to their constituency for what they do in the locality. But no one will be responsible for how the country runs. .
(iii) India also has non-party based elections to the panchayats in many states. Although parties do not contest formally, it is generally noticed that the village splits into more than one faction, each of which puts up a 'panel' of its candidates. This is exactly what the party does. That is why we have political parties in almost all the countries of the world.
(iv) The rise of political parties is directly linked to the emergence of representative democracies, large-scale societies need representative democracy. Large societies needed some way to bring various representatives together so that a responsible government could be formed.
We can say that parties are a necessary condition for a democracy.