This is because words actually don't carry much meaning, they invoke something that the other side understands already. For example, it's very hard to have a conversation about some aspects of a relation of 40 y/o people if the other party is in their 20s. You need to relate with something of their age and build it up and even then its likely they will understand it completely the wrong way. Over the years people evolve, they go over stuff and when you meet someone who hasn't been through the process you need to be aware of that otherwise you will mistake them for stupid(because, not everyone who ages ends up going through the transformation the same way. You better know if you are speaking to such a person or a younger person who has the chance).
What I don't understand is, why people assume that everything you know about someone is supposed to be used against them. Why everything needs to be malicious?