There are many ways to contribute to public life. We can do this by offering our time, volunteering, becoming a candidate or being elected. We can also contribute by making a donation. It's a way of expressing a political position within a democracy. I would say that political parties also have a connection with their activists who are contributors.
Who is a political party accountable to? The electorate, obviously, if elected, but it is accountable, first and foremost, to its members and the laws governing it. When members don't provide the political financing, or provide less of it, it's as if the power we give to members, activists, is much less present in the distribution of a political party's internal power.
I would say that it is part of the anchoring of a political party in society. I'm not talking about large donations; I'm talking about commitment, in different forms, of activists in a healthy party life. If we cut this link or make it more difficult, I'm afraid that some political parties will no longer be representatives of civil society in government or parliamentary institutions, but will be more like representatives of the government in civil society. So I think there is a major link between them.
At the individual level, contributing to a political party and expressing one's opinion financially is a democratic right; it's not just about giving time or volunteering.