It’s to defend against assholes like Keith Ellison and Bernie Sanders, should they get their way and attempt to pursue their eliminationist agenda:

Ellison’s ‘Extremism’ Charge Deflects from Own Subversive Affiliations

“Oath Keepers and Three Percenters [are] extremist anti-government movements,” Rep. Keith Ellison charged in a CNN hit piece we talked about in my last column. I noted then we’d take a look at the pot dissing the kettle, and now seems as good a time as any.

[…]

I’m going to focus on Ellison’s membership – and leadership – in the Congressional Progressive Caucus, founded by Democrat presidential contender Bernie Sanders and containing 69 of the most rabidly left-wing politicians to ever menace the future of the Republic. Or as Obi-Wan said about Mos Eisley, “You will never find a more wretched hive of scum and villainy”…

Importantly, one of the CPC’s core “principles” is contempt for the right to keep and bear arms. They know that every tyranny that ever beat its subjects into dehumanized submission had to first disarm them, rendering them pliable, subservient and helpless.  But don’t take my word for it – take theirs, paying special attention to their demand to ban firearms of militia utility.

OK, so they’re typical Democrats. Is that all I’ve got?

Well, yeah, that and pointing out the CPC’s close ties with another “progressive” group, the Democratic Socialists of America.

[…]

Do you like songs? So does the DSA, so much that they devoted a page on their website to hymns glorifying their “struggle” (i.e., what Hitler called “Mein Kampf” ). The following in particular should be of special interest, since the people they’re talking about, the “bourgeoisie,” are you and me! And they really explain (better than anything I could say) why the socialists need to take away our guns. Ready? All together now:

Are You Sleeping, Bourgeoisie
(Traditional American song, sung in rounds to the tune of “Frere Jacques”).

Are you sleeping, Are you sleeping,
Bourgeoisie, Bourgeoisie,
And when the revolution comes,
We’ll kill you all with knives and guns,
Bourgeoisie, Bourgeoisie

—–

Bourgeoisie, Bourgeoisie, See How They Run
(Usually sung in rounds after “Are You Sleeping, Bourgeoisie”. Sung to the tune of “Three Blind Mice”.)

Bourgeoisie, Bourgeoisie,
See how they run,
See how they run
And when the revolution comes,
We’ll kill them all with knives and guns,
Bourgeoisie, Bourgeoisie

Don’t try to look these up at the DSA’s website; they sent them down the memory hole long ago.  The Internet Archive, however, is your friend.