I think its great for people to share their opinions, experiences, research etc. I think what the OP was trying to get at (and I have seen this too, not here on BB but other places on the web) was the implication (sometimes spoken, sometimes silent) that if you choose something different you are somehow less of a mother or less of a woman. I think that is where the bullying part comes in.
Birth is an intensely personal experience and no-one should presume to dictate to someone else how they should have/ should do it. We are very fortunate to have choices and information that can help us make decisions about how we want to give birth. To a degree we will always be flying blind coming into our own first birth experience - no matter what others tell us, how many books we read etc - we just don't know.
Birth is a natural process but things can go wrong. Interventions can be necessary and life-saving. They can also be designed for the convenience of doctors or the legal butt-covering of hospitals. The really hard part is that while you are in labour an intervention that is for convenience or butt-covering might be pushed on you as being life-saving and necessary. And in the midst of the experience, you don't want to take a chance on something happening to your baby. That's why we need to research, share information, support and encourage each other. What we don't need to do is play my birth was better than your birth and therefore I'm a better woman and a better mother than you. Like I said, this is not an attitude I've seen on BB but it's definitely out there.