I wouldn't say Barrett's destroys the les. It's more the other way around. The lack of a functioning les for a long period of time leads to Barrett's.
Here's a good video that talks about
the progression of GERD as it relates to the Linx. It's a little long, but quite informative.
toraxmedicalspringlectures.com/lecture_ch.php?lecture_id=144&check1=02e74f10e0327ad868d138f2b4fdd6f0