Brand communities are more effective technique to enhance brand loyaly. Do you agree with this statement ?

Yes however depends HIGHLY on the product, the market and your target. 

Nowadays there is too much brand communities and so the techniques needs to evolve and to readapt. Because It has become so obvious that it is no more impacting people. And most of the largest companies are burning too much money for a low ROI

i.e. even when you are buying a water bottle, marketers will purpose you to join the brand community to gain for points that could be use for your next bottle purchase. I don't know anyone that is still collecting points and buying this kind brand communities