Imo this comes at least partially down to the generic pattern of representatives becoming more conformist when they get into power. In my country for example we have a Pirate party, and they were quite radically progressive when they were founded but as they got into parliament+govt they became more centrist. You see this happen in many countries. I wouldn’t immediately jump to the conclusion that they are being ‘vetted’ by hidden elites, I think it’s very possible that its just an effect of the incentives you face in the process of competing in elections, facing the media, the environment in a parliament, etc. etc. But even if the latter is the case, it wouldn’t be a good thing since you have a diverse set of representatives representing a diverse society, and if the democratic system molds them to have a uniform set of traits then you are losing accuracy of that representation.
Hmm… Volt?