Well, the reason something like DI water or referse osmosis is recommended is because it gets out a lot of the small particles in water that can clog your nozzles. And supposedly something like DI water is healthier for you, although I still have to be convinced. So as long as you think your tap water is drinkable, go ahead a use it if you want. There are ways to get nozzles unclogged, like using vinegar, so there are remedies if anything happens. Or worst case senario you have to order a new nozzle.
It really depends on the source of your tap water. I am lucky, the water we get is very clean (not alot of chlorine, fluoride and no salt or hard metals). If you live in a city with lots of junk in your water you my want to at least run your water thru a Brita Filter (or RO/DI filter).
It will all depend on your minerals and local water treatment process. If you are living in an area with hard water, your nozzles will clog pretty fast. Most places people will have the chemicals to deal with in the water. Some locations have better water treatment than others, and it will all boil down to what you have locally, not what people say is right or wrong. Ideally you filter the water with a carbon filter that can absorb the chlorine our of the water.
I personally use RO water because I live in an area with hard water.