What happened was, folks on the left noticed, correctly, that folks on the right would sometimes use racially-coded behaviors as stalking horses to express racial animus. Dogwhistling, we called this, and there was something to it. 

Ranting about Mexicans wasn’t such a hot look, but ranting about illegals…ok. For black people, it was crime. Same thing. Many on the right were not subtle about this, and it was very easy to spot what they were doing. 

But then in response to it, folks on the left came to fear that even lodging valid complaints about those behaviors could get them tagged as racists. So they stopped doing it.

And they began adjusting their policy stances to avoid those charges, with no real principle or desired outcome to guide. Illegal immigration wasn’t that bad, actually. Neither was crime. 

This was a big deal, because there used to be a broad, bipartisan consensus that any form of lawbreaking was bad and needed to stop. To the extent there was disagreement, it was over how best to mitigate, not whether mitigating was even worth attempting. There were fringe outliers too, but not many.

This new change was major. The Democratic party platform effectively just dropped both issues, because there was suddenly no safe way to talk about them. People are not nuts for noticing this, and it was not the result of any earnest shift in attitudes. It was about cowards being afraid of getting called names. Little more.