exactly, because they are easy to test for. while there are understandable reasons for diuretics to be in a player's system, there are also illicit ones. rather than playing whack-a-mole trying to come up with ways to test for every new substance, they have decided to flag the most popular way players try to cover up PED use because it's so much easier to test for. And I'm speculating there are far fewer ways of covering up PED use than there are PEDs. So they've put players on notice - if you test positive for diuretics, you're suspended, and it's up to you to prove in any subsequent investigation why you might have legitimate reasons for diuretic use.

it's like if your momma wanted to stop you spoiling your appetite before dinner, she could set up all these ways of trying to figure out how to catch you in the act of taking food out of the fridge or cookies out of the pantry or whatever. or she could just ban you from the kitchen. if you go in the kitchen, you're grounded. she buys a cheap motion detector that sounds an alarm. alarm goes off, you're in the kitchen, no modern warfare for 25 days. it's now up to you to prove what legit reason you had being in the kitchen.