If you had two objects that are so far apart that the distance could not/never could be measured, would you call it infinity? Then suppose one of the objects were to move an extra unit away from the other so the distance became infinity + 1, but that isn't the same distance as 'infinity'...
Infinity is qualitative not quantitative, as in, it is there to describe what IS not a number to represent what is. Its only purpose in maths is to be a pretty symbol that fills a gap that can't be described in maths, and any equations with infinity in it is meaningless in real life until the infinity is removed.
And no, I don't really know what I'm talking about