Likewise, the libtard is someone who has the brazen audacity to question conservativism from their position of ignorant hypocrisy to the point that we must assume their liberalism has "tarded" their brains all akimbo.
And a cuck is short for cuckold which of course means you're a dude whose wife sleeps with other men. But somehow that has something to do with liberalism now. Like maybe you're so liberal, you have an open marriage? Or your tiny snowflake genitals are so decrepit that your lady is forced to lie in the arms of someone who regularly quotes InfoWars? Honestly, I'm still trying to get this one.
Why it Fails:
Maybe they just mean you're a p***y but don't want to say p***y because p***y is more offensive and women are less apt to want to throw that one around. But let's be honest, that's what they mean. So you're a p***y. Libtard essentially means the same thing -- you're liberal, which is to say overly sensitive and pussified, and also retarded. But they don't want to say retarded because that word is offensive too, and this makes them feel better.
So essentially we have two words that are designed to mask offensive things, you know, in a sort of overly sensitive and pussified way.
As for cuck, well, if you like your wife f*****g other dudes, then you're probably fine with that. It's a whole genre of porn, you know. Just not sure what it means in the realm of politics. May as well call someone a kazoo technician.