I think "soundguy" brought up good points......everyone camps differently, so one method doesn't work for everyone! I'll be the first to admit, my sh** stinks. Many full timers who are parked for months say they use just water, well that's great, you're not getting the suction/pressure issue that's created while driving.
Others say theirs doesn't smell, except when you dump and the rest of the park has to smell it. Those whose toilets drain straight down into the tank, will also get odors when they flush. No matter how much you argue this point.....the stuff still smells and if it escapes via pressure while driving, or during dumping or while flushing, it's an issue.
I used AquaChem for probably 30 years. It only masked the odors, but helped. In the last two years, I started using Happy Camper. It actually converts the waste to a relatively pleasant smell. I could run my system with just water because we dump often, but on those occasions where there is a vent near my dump, or it needs to stay in the tank a few days, I would rather have a chemical added.