Using bacterial and fungal harboring leaves, because what's potentially altering your gut microbiome (I urge you to look up FMT and how it's performed), which has repeatedly been shown to control countless wide ranging things from psychological to epigenetic to health related topics, when you're trying to save 0.15% of your body weight from your pack.
It's my personal opinion that sometimes there is more to gear choices than simply weight. As a quick example, not using full coverage while sleeping outdoors in New England. Ticks which carry Staph, Lyme Disease (which current research indicates may never be eradicated from your system), and numerous other bacterial pathogens, which is to mention nothing of flying insects (EEE anyone?). Sure, you save a few ounces (keep in mind, 1oz for a 150lbs person is 0.04% body weight) by not packing an enclosed sleeping arrangement (or in this case toilet paper), but you run the risk of potentially picking up a viral, bacterial, or parasitic infection that may lay dormant for years.