The more accurate the map, the more it resembles the territory. The most accurate map possible would be the territory, and this would be perfectly accurate and perfectly useless.

This quote hides a subtle equivocation, which it relies on to jump from "you have X" to "you do not have X" without us noticing.

If I have a map I can look at it, draw marks on it and make plans. I can also tear it to pieces and analyse it with a mass spectrometer without it damaging the territory. Make the map I start with more accurate and I can draw on it in more detail and make more accurate analysis. Make the map nearly perfect and I can get nearly perfect information from the map without destroying breaking anything in the territory. Moving from 'nearly perfect' to 'perfect' does not mean "Oh, actually you don't have one territory and also one map. You only have this one territory".

As a practical example consider a map of a bank I am considering robbing. I could have blueprint of the building layout. I could have detailed photographs. Or I could have a perfect to-scale clone of the building accurate in every detail. That 'map' sounds rather useful to me.

Imprecision is not the only purpose of a map.