I haven't met any chameleon masters that recommend using water bowls... seriously, check the credentials of the people giving you info. This forum has people that have kept rare/unique/tricky species, bred them, have years and years of experience, etc. None of them will recommend using a water bowl.
All of that said, if cleaned daily, I think it is safe and if you want to use it go ahead. I more so question the other husbandry(not saying yours is certainly wrong-IDK) because almost anytime we see someone using a water dish, everything else is off too...wrong uvb, few plants, poor diet, etc. Again, not saying that's you, but the bad advice people get often comes in a bundle. We also see people that want to do things differently, just for the sake of doing things differently and then they disappear because their chameleon got sick or died and they don't want to admit they should have listened. So that's why everyone's being concerned, not that they want to be hard on you.
Also to give you the benefit... I have kept 3 different species, right now I have a 4 year old yellow lip calumma parsonii parsonii and he is thriving in a very unconventional way. I only do this because it is what works for my situation having such a large chameleon, but he is kept on a free range, gets water for 1-2hrs in the shower 1x per week(mist setting) and I fog near him for about 5 hours, 4 nights out of the week with a dehumidifier running so the room doesn't turn into a swamp lol. Other than that, he eats a lot and gets no other water, urates are always white and moist. I do think they retain hydration pretty well from whichever source they can get it. Point being, if he's drinking from your water bowl, it's cleaned thoroughly and regularly, fecals/urates are good, and other husbandry is on point, then I think it'll be fine even if it's not the generally recommended way.