The legislation not only needs to pass the Senate and the House, but also various committees and the president must also typically sign it. Each one of these hurdles reduces the chance of successful legislation which tends to favor the status quo. As noted by James Madison in someone else’s post, he thought the Senate should favor landowners over the majority “to secure the permanent interests of the country against innovation”
Arguably this inherently favors conservatism as passing no new legislation will keep things the way they are. Progressives will, in most cases, need to get legislation or referendums through to make meaningful changes to the current system.
Florida seems to have figured this out. This election there is a referendum to require voters to approve all new referendums twice to try to decrease the number of successful referendums.