There's nothing wrong with including yourself in the picture. The issue is when your presence isn't needed, yet you for some reason decide to make yourself the focal point instead of the object you're trying to show your audience.

Let's look at some of the examples you provided:

This guy has a reason to be in this picture. You can clearly see he's holding the cat's arms in place.

This guy's presence actually adds to the picture. There are plenty of more professional versions of this picture in outdoors/nature magazines.

This guy is holding the owl in a blanket. Again, his presence is needed in the picture.

This guy is showing off a scarf, which is an item that you wear on your body. That's a perfectly valid reason for him to be in the picture.

This man is replicating a picture he took of himself and his dog when he was younger.

This is a picture of a guy meeting a celebrity. It's pretty common to include yourself in pictures of well-known people. How else would you prove that you actually met the person?

This user is showing the damage done to his helmet and face after experiencing a wreck of some sort. There shouldn't be a need for an explanation for why he includes himself in the picture.

This user's body language adds to the picture.

This person is showing off a hat, which is an object that you wear on your body.

This picture wouldn't make much sense without the user's presence.

This user is seemingly showing off a friend or family member's shirt. It would be pretty awkward if he asked the person to take off the shirt so he can get a picture of the item by itself.

Whoever created this list apparently doesn't know the difference between including yourself in a picture when your presence actually adds to the photo, and making yourself the main center of interest in a picture when your presence is entirely unneeded.