[quietolong]

It’s because there trying to name it from the imperial formula. They vaguely remember something from wayyyy back on how chemicals are named.
Water is fairly simple. But other more complex chemicals can have many of these types of bonds. Making the true formula somewhat long & obtuse. And when you just want to know what atoms are in something. So the chemist just simplify. They add up all the atoms of each type and write that down.
Most of the times the imperial and true formula are one and the same.... But not all the time! Water is one of those not all the times.
It like for those of you who remember learning how to balance chemical equations. You think you got it this is simple..... Then your teacher throws you some Redox equations at you. Some of those special cases where the normal way of doing it don’t work
And then we can get into Hydrides.....;)

[Lawgvr1955]

It like for those of you who remember learning how to balance chemical equations. You think you got it this is simple..... Then your teacher throws you some Redox equations at you.

That is why I ended up in law school...no math.