In an ideal world, maybe that's how it would work. In reality, that's not how it works or likely ever will work. So the comment you're replying to is a pragmatic approach to "how do we make the world we actually live in, not some idealized fantasy, safer?"
In reality, Trump's tough on illegal immigrants approach has drastically reduced the number of illegal border crossings compared to Biden's term.
So, it seems that "people living in the country illegally" doesn't have to just be a fact of life, if there are federal policy changes that can radically alter the number of people who illegally enter the country.
Sure, if this is true... and it only came at the cost of due process.
Even if you prevent everyone from coming here illegally, you'll still have "illegal" immigrants. I would wager most illegal immigrants came here perfectly legally.
Illegal border crossings are a distraction. The vast majority of "illegal immigrants" entered legally and overstayed their visa. This makes "radically altering the number of people entering illegally" a fairly meaningless achievement in practice.
For all we know those very same people who would have crossed the border illegally are now spending the extra money to enter legally and overstay: same number of incoming "illegal immigrants", but via different pathways.
