because everyone dips at different depth and not all opinion is equal, but when someone just says it, you have no idea how much thinking he has done, and the subliminal impact on your own thinking with unfiltered sharing can be quite negative. deep thinkers should actually be reluctant to share their opinions because they are the results of hard work, or even more so--reluctant to hear other people unload their shallow thoughts on self. it is precisely those who haven't put in enough to feel that reluctance becoming the ones that want to 'share' and 'exchange' all the time, and in fact they are the ones easily influenced too, perfect circle.
i always treat my view as being "the view" and until something dawns on me, i may begin another process of critical thinking, the process itself actually becomes more important than your advancing conclusions because you learn how to manage the process and you get better at the market senses 'i am sure i am right this time'. with hearing what others say all the time, you don't nurture that cerebral process at all. it's like self discipline in a way, unless you do it yourself, you won't know what i'm talking about.