In the end, it's obvious to everyone that the US can't just let people keep entering the country illegally - but it's equally obvious that it does need to, firstly, process asylum requests correctly and quickly enough (which I understand will require large investments in staff and infrastructure to process asylum requests), and secondly, help the Northern Triangle countries deal with their massive problems that are driving the exodus, to which the US has directly and indirectly contributed over the past half century or more. I would hope that Harris' visit also leads to significant progress on that second point.
AOC criticized Harris for saying that Guatemalans shouldn't come as they would be turned away - and indeed, they should still have the right to make asylum requests and be accepted depending on the outcome, so Harris shouldn't take it for granted that they'd all be turned away. But it may still make sense for the US to try to shift the asylum requests from the Mexican-US border to its Guatemalan/Honduran/Salvadorean embassies or consulates.
For sure, on immigration like on so many other topics, the political debate in the US is often rather beside the point, obsessing over optics and rhetoric while paying little attention to less spectacular but ultimately more important issues, like in this case the investment required to process asylum requests faster.