In this question: Why did they build the Wall in the first place?
Given that dragonglass kills the Others wouldn't it be easier to equip armies with dragonglass weapons than build a Wall this massive?
and there was this answer:
The wall was built by the first men. The white walkers drove them south to settle the land of westros. The wall was built to keep those dangers from engulfing the whole continent.
But OP clearly said that those dangers can be defeated, thus there is no point in the Wall.
This answer doesn't answer the question at all.
It answers a question like
What is the point of the Wall?
But not a question like OP's which was
What is the point of the Wall since there is an alternative ?
I flagged this as 'not an answer' but my flag was
declined - flags should not be used to indicate technical inaccuracies, or an altogether wrong answer