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?
Its useful to have an outsider to look at this thing from a different perspective but they still need to be at about same level. It's extremely rare to have an unrelated genius, %99.9 of the time the the outsiders are people who didn't go through the basics that a homogeneous group went through and they just do a speed run on the basic ideas that everybody first though but didn't work. Still shouldn't be dismissive, has its place when the established understanding strayed away from reality but its not possible to base all the discussion on such a composition.