Maybe people would still be poor in Central America if not, but the US has a responsibility to deal with some of the consequences after decades of destabilization and intervention in the region.
There is no nation on Earth that just throws open their borders as is repeatedly asked of the U.S. in recent years.
It is true that the U.S. has a responsibility to its neighbors. It doesn't follow that open borders are the same thing as taking responsibility. In fact, open borders are the opposite of responsibility.
USA doesn't need to open its borders indiscriminately, what I'm saying is that it should take responsibility for some of the fallout of its own meddling with Latin American democracies and economies.
Indiscriminately opening the borders is just as bad as indiscriminately closing them, there should be a fair review process to accept some of those refugees. Expecting Mexico to become "the wall" will just stall the humanitarian crisis a few years.
It is true that the U.S. has a responsibility to its neighbors. It doesn't follow that open borders are the same thing as taking responsibility. In fact, open borders are the opposite of responsibility.