Unlimited point earning is easy to exploit, other platforms have similar restrictions to avoid people just spam-creating a bunch of memes solely for points. We had less exploitation after adding these.
Imgflip would like to encourage diversity of creators, opinions, and content categories, which these point strategies help with.
Also, whether people want other people to have points is totally irrelevant, because that's not what Imgflip points are about. If you want your friend to have 1 billion points and be at the top of Imgflip, that's great for you and your friend, but it's a total shit experience for everyone else because it's unfair and their points are now useless. Unlimited point earning makes it easy to just go upvote all your friends old images to massively inflate their points, not because their content was necessarily enjoyable to you, but because you like them.
Imgflip points are designed to help the entire community find the best content.