The problem is that you're likely consuming the content of extremely young and likely inexperienced and undereducated people who've barely made it through a high school lit class. That's fine, but the source of the opinions you consume also matters if you're looking to expand your own intelligence and literary analysis. This depends on your goal, though. Finding someone who likes the books you like is great for those para-social relationships and building wonderful echo chambers, but also for finding real life book recs. But, the truth of the matter is that good opinions exist, and some people's opinions matter more than others within a certain scope of criteria. It's absolutely silly to say everyone's opinion has the same weight regarding art.

We can engage ethically or aesthetically, for example. We can judge the morals, the quality of writing, composition, style, etc. Those are all valid criticisms, and some may boil down to preference. I personally think we should all be critically engaged with the media we consume, including literary art. Nonfiction holds an even higher standard, btw, so if you find someone speaking of "all opinions are good, and no-one is better", please run as fast as you can after politely telling them what a load of utter codswallop it is they're spewing.