I was unsure when I made my post a few years ago, but strangely enough, I remember now.
I found the link about a year after I found it the first time…
It was on Wikipedia on the nightmare or LD page, and it said “some lucid dreamers believe that it is a good treatment for nightmares” and it cited a source, the source was the LD4all guide.
Since then, of course, they removed it and put on actual studies.
EDIT: Omg this is my 911 post, someone help me!