I don’t "hate" the other brands. I think they have a place. They keep Lego® pricing competitive. Would I buy them, no. It comes down to two issues for me. Quality of brick and misnaming. I hate that many non-Lego or non-brand specific buyers/sells refer to all brick toys as “Lego”, when there is a clear difference. This would the same as selling a Samsung Galaxy Tablet 1.0 and calling it an iPad. Sure they’re similar and they do similar things but they are not the same and should not be sold as the “same” product. Which is often the case in yard sales, Ebay, etc. You'll often see a "pile of Lego" and when you look at its building bricks from China that someone got in a Dollar Store.
"Porsche* for sale!"
*Porsche logo has been applied to Yugo for your pleasure.