I am not sure it is so common, but in short members apply. Usually for good reason in my personal experience, though am sure it has been abused.
Depends an awful lot on the site you cam from, some are model centered some are member centered.
I started on a member centered site and charged back every so often, say when a pvt went wrong technically or from a model milking extra credit. It worked well in that you could redo/ partially redo an experience or spend on someone more deserving of your spend. I learnt who to spend on from lowering the risk. I don't think the site benefited or lost much from this position in hindsight.
I later switched to a model based site and soon learned to spend on risky models and cam feeds at my own risk without the safety net. On this kind of site charge-back is pointless. You lose sometimes from your risk, but the lessons can be worth it. You tip more, and spend less time pvt or in group. Model based sites definitely work better for those you already know and allow for more social time with the model. It can be a richer experience as a result.
In short my answer to your question is that you have joined a member based site, hence more charge-backs. They favor customer service over the freedom to make the wrong choice, members must legitimately consent to spend on a model... i.e. no buyers regret, so they are less likely to leave after spending.
IMO sites offering easier charge-back are a good place to start for members, experienced members will gain a deeper experiences with sites taking more risk with their credit.