You're right and I think the commenter was sprouting bollocks. Reddit used to be plagued with comments like that which are simply meant to cast doubt, and aren't based on facts.
I've tried a few alternatives since Reddit closed and Lemmy by far feels like the logical replacement. Super simple and I can see how it'll just grow from here.
You know who's not 'pouring into America'? People with options.
Unless you're fleeing the third world, I can't imagine why America would even be on your radar. He's obsessing over the wrong problem.