interesting discussion which i am late to but have an opinion on!
while i might not call it stealing, i do think that once you open up a book, newspaper, magazine (whether it is to review or read) you irrevocably damage that product. if you open it and then dont buy it, it might actually be more akin to vandalism.
but then again i am that kind of person who feels something rewarding by opening up a newspaper or book for the very first time.
i very rarely buy physical copies of anything anymore, but for sure if i see a crease then i am 100% not going to buy that copy. its damaged goods!