Can someone explain the logic behind wanting legal immigration?

So, I made a question about the logic for open borders a few months ago

Can someone explain the logic behind an open borders policy for a country?

Now I'm moving onto legal immigration

I'm sure there's plenty of emotional arguments for wanting legal immigration

but are there any logical arguments for needing legal immigration?

as in it'd be an absolutely detestable travesty if legal immigration was completed banned period and is considered one of the worst things imaginable

Can someone explain the logic behind wanting legal immigration?
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