> While it may partly work in a small geography with a largely homogenous culture (like Switzerland)

Homogeneous as in 4 different language and cultural groups? Are you sure we're talking about the same Switzerland? Not to mention tons of migrants from all over Europe and the wider world?

The real problem with direct democracy is that most people are shortsighted. Governments often need to make long term decisions, like infrastructure, combat climate change, etc. and those are simply too big to be fully appreciated and grasped by your common voter - point in case, new "green" laws to reduce CO2 emissions were recently refused by referendum in Switzerland - https://www.bbc.com/news/world-europe-57457384