I think if you try and confuse folks with this, that is easy to do. But, this isn't special. What happens if you add a meter to a kilometer? For most measurements, you get a kilometer. We teach this with significant digits, but then typically ignore it and assume all sorts of conventions that are not spelled out.

If it is important in the domain you are working in, take extra care to understand the maths that you are built on. And don't be surprised to find special cases everywhere.