That is a myth druid put about by people who don't use braid shockleaders. The only time a braid (or nylon for that matter) shockleader will cut you is if you don't tighten your drag fully up when casting. I used braid shockleaders for years and never once got cut. I've gone back to mono as a 1000m spool of 15kg line is way cheaper than decent braid as a shockleader.