I can't speak for this instance, but I've received "free" items from sellers on Amazon numerous times in exchange for a review. YMMV.
Comes down to personal choice. I've received some good, quality items at no cost other than leaving a review that required minimal effort on my part. Any item I've received were items I was interested in purchasing anyway.
Not 100% but I think being chosen had to do with purchasing similar items from the seller before, products in their line, and providing reviews on items I purchased. I've also done Google Rewards for several years. To date, I've earned $124.13 by taking their surveys that literally take seconds. The $$ earned has to be used in Google Play, which is fine with me. I've used the earnings to purchase books, movies, apps, games, etc.Just wondering, were these things you had looked into or contacted sellers about? Why were you chosen? I've never received any of these offers. Wondering if it may be that I was employed by Amazon for a few years. I do look at many brewing items, am a Prime member and buy a lot of stuff from them.