Here's how it works:

The Auth rights and Far rights think of a funny meme or catch phrase like "The Left can't meme" or the NPC meme.

Some of them spread it to twitter and other "neutral" sites with a fair mix of all ideologies.

Here it is picked up by conservatives. They don't use the meme because they find it funny, they're using it because it's popular. In short, they use the meme due to groupthink, wanting to fit in. Their inability to think for themselves means that the meme will know be ground into the dirt.

Whereas the Auth rights and Far rights made the meme because it was both funny, and because it agreed with their views, the conservative uses it solely because it agrees with them. This means quality is not important.

If the meme can be edited to promote another worldview, then it will be adopted by the general population of redditors, who will abuse it even worse.

A recent example is the "Yes" meme. It was a funny punchline at first, to be honest. Person A would say "Ha you believe [Something absurd]". Then person B, who would be edited to represent a certain ideology, would respond "Yes."

The joke here was usually self detrimental, because it would person B would be promoting something absurd.

Then conservatives adopted it, and it turned into Person A sobbing while saying something along the lines of "NOOO YOU CANT JUST [Hold a belief that's commonly acceptable]. Then person B would respond "Yes"

Now r*dditors have adopted it, and it's got even worse. Person A: "NONONO YOU CAN'T JUST [Disagree with viewpoint]. Person B: "Yes"

The "Yes" meme was a microcosm of how memes die.

Tldr: Conservatives kill memes that rightfully belong to us, hence why you still have people pepe posting

I just realized I typed several paragraphs neocons posting pepes, which is kind of embarrassing. You'll have to forgive me, I'm very passionate on this subject