My $.02...
People recommend what they own because the purchase decision was considered beforehand, and they have already went through the purchase process, which involves forming beliefs. This forms bias, but online it can be hard to distinguish between whether the recommendation comes from pride of ownership or is an objective recommendation without bias. I think it's always a combination of the two as it's impossible to fully detach yourself from bias, but some are more successful than others in understanding and overcoming bias. Some understand their beliefs are not who they are which makes it much easier to reduce bias.
