The problem is that the vast majority of my non-grocery items are not purchased by my friends & colleagues so word-of-mouth information isn't available. E.g. I buy stuff like hi-end camera gear, woodworking tools, audio equipment. Even more common items like books don't work because my friends don't read the same type of books I do.
Even your example of a computer monitor doesn't work in my situation. About 15 years ago, I wanted a large 30" monitor but none of my friends had that so I have to research on my own. Likewise, they also can't depend on my experience with computer monitors because a big external 30" monitor is never something they'd need because they just use the builtin laptop screen.
A lot of times word-of-mouth works great for recommending local restaurants or grocery items such as the Costco brand of paper towels and olive oil being good buys. For all other items that your social circle doesn't buy, you have to research external information sources.