Technically, most mammals go through a similar process as humans do when it comes to sex, although face-to-face is unusual in the animal world. With a few exceptions, the mechanics are quite similar as well, but the variation is usually considered to be that most mammals haven't been proven to engage in sex for pleasure, as humans definitely do.
The main reasons that people have sex are to create life and for pleasure. Animals have those same instincts. Animals may not have sex as often as humans, but certainly they have sex for the enjoyment as well as for reproductive reasons. If it was not a pleasurable experience they would avoid it.
I mean, many of them obviously don't, but I'm not sure what the debate really is here. Humans have studied the sexual behavior of other mammals, and while there are plenty of similarities, there are plenty of differences, both in terms of the biology and the psychology. Unless whoever wrote this doesn't think humans aren't mammals?
All mammals are different in some way. Some mammals reproduce the same way humans do while some do not. It all depends on which mammal it is. Every animal is different in some aspects and the same in some aspects and sex is one of these aspects that may vary or be the same.