Apparently so - if you look at the “Customer Questions and Answers” section of Amazon product pages, there is a remarkably high proportion of answers like, “I don’t know, I haven’t opened it yet” and “I’m not sure, I bought it as a gift”.
If you bought product X and some months or years later “Sam” posts a question on Amazon that isn’t answered, Amazon will send you an email with a subject line that is a variation of “Sam has a question for you about Product X, can you help?” and the body would be something along the lines of “Dear foo, Sam wants to know if <insert question regarding Product X here>? Click here to respond to Sam and help her out!”
In that context, you can easily see why people reply with such otherwise useless “answers.” When someone personally asks you a question you don’t know the answer to, responding with “sorry, I bought it for my husband as a gift and I don’t know,” is not just perfectly valid, it’s also the polite thing to do. But that answer is posted to the website in the genera Q&A as of you had viewed the question and then instead of passing on a question you had no answer for, you chose to reply with a useless answer.