The wall is force multiplier, ask the Israelis.
You’ve got to understand, the anti fence clowns use the strawman argument that a fence wouldn’t be enough. That much is true but no one is saying a fence is the only thing needed.
There needs to be real enforcement and patrol as well. Unfortunately, you’ll find they have plenty of arguments against those measures as well.
The border fence at San Diego (Duncan Hunter’s fence) has been quite effective. Obviously not 100% effective but no fence could be.