Sharing the road is dangerous with dangerous, aggressive drivers. Tailgating and bumping bikers is the fault of the driver, not an unavoidable consequence of sharing the road.
[Lots of places beg to differ](https://www.treehugger.com/bikes/dutch-kids-have-different-r...).
You can't bully people into being good, but there are lots of nudges like education and more thoughtful design that can move culture to work better.
It works fine if people adjust their expectations. Cyclists in the way rarely cause real stretches of backed up traffic. Your average speed might go down slightly, big whoop.