"Vehicular Cycling" is a survival technique where cyclists are a small minority without proper infrastructure. It's widely practised in the UK and USA. Indeed, when I lived in the UK, I also cycled according to such principles. In its own context, in a country with a minority cycling culture and no real government support to enhance infrastructure so that cycling can grow to its full potential, it makes sense.
However, if cycling is to become "normalized" - i.e. something that the majority of the population sees as a part of their life, which parents encourage their children to do, and spouses encourage their partners to do, then it needs something different. All three types of safety become important. Dutch cyclists are the safest in the world due to infrastructure which keeps them apart from what is the greatest danger to any road user: motor vehicles. They also feel the safest due to street designs which emphasize both social and subjective safety, and this leads to a very high degree of participation.
Dutch cyclists are not only the safest in the world, but also the Dutch cycle more than people of any other nation. Almost the whole population (93%) rides a bike at least once a week. Every type of person cycles. During weekdays, more than a million journeys are made by bike every hour. The infrastructure is the reason why.
Unfortunately, some cyclists from minority cycling countries still don't understand this, and some campaign aggressively against the very infrastructure which could help to bring a higher cycling rate due to improvements in subjective safety. This video from Mark Wagenbuur shows some of the commonly repeated mantras of the more aggressive anti-cyclepath "vehicular cyclists" and demonstrates how they are misleading and wrong, at least when applied to properly designed infrastructure as shown in the video, and as is the norm in the Netherlands.
Well designed cycle paths, and streets designed to prioritize cycling over driving, increase both the safety and speed of cyclists.
Some people may question whether cycle paths as in the Netherlands are necessary to achieve mass cycling. My answer to this is very simple: There are no counter-examples. Mass cycling has not been achieved anywhere in the modern world without cycle paths. The more money spent on cycling, the better the result. Luckily, even the best infrastructure in the world isn't actually that expensive, and cycling is something that any country can afford to do properly.