There are so much love for bicycles. I'll offer something from the other side that people who drive. What I really find it scary is that cyclists often take the road as they wish and then block dozens of vehicles, or do something else that might seem to be quite normal from their perspective, but nevertheless is dangerous from drivers' perspective (e.g. suddenly get into road from sidewalk, are you going to cross or not?)
Basically, if the road you are cycling on are not reserved for cyclists, I'd say you are putting yourself and other people in risk. My city has a lot of cycling lanes but unfortunately not every road has one.
Cyclists take the lane and "block vehicles" as a safety measure, not for some hatred of cars.
"...cyclists drive in the middle of the lane because it actually protects us against the most common motorist-caused crashes. Our top safety priority is to ensure vantage and visibility (to see and be seen). Bicycling in the middle of a lane is our #1 tool for defensive driving."
Laws vary widely of course, but for example, in my state, cyclists have a right to all roads except limited access highways.
They are meant to keep as far to the right as is safe, so for example, to execute a left turn you enter the middle of the lane and follow the same path a car would. Or another example, if there is a parked car blocking the right side of the street, the cyclist can take the center of the lane to go around the parked car.
The law definitely permits, but law doesn't override risks. I do believe bicycles should have separate lanes and my city already have a lot of them. Not enough in some older parts of the city though.
The road isn't reserved for cars either, despite what you might think when you see a cyclist "blocking dozens of vehicles" when he's just using the road.
A bicycle has the same right to the road that a car has. Just like you'd have to slow down for a tractor, you're supposed to slow down for bicycles as well.
Roads exist for all road users, not just for drivers.
Basically, if the road you are cycling on are not reserved for cyclists, I'd say you are putting yourself and other people in risk. My city has a lot of cycling lanes but unfortunately not every road has one.