One issue preventing such parties, is that people do not have time and interest to think about all the issues and there needs to be a way to delegate and trade votes.

In Australia there is https://voteflux.org which solves the first issue.

But another issue is lack of an easy way to onboard new people, because now a party needs to gather a large support to become useful. Maybe if they partner with a petition site like change.org that would both try to influence existing politicians and serve as a way for new people to get involved with the real thing, they would get the necessary viral growth.