Coining new jargon words (neologisms) is an alternative to formulating unusually precise meanings of commonly-heard words when one needs to convey a specific meaning.
A Marxist may use the term "surplus value" to specifically mean the difference between a worker's productivity and wage. If they say "surplus value" to someone who does not recognize this specific meaning, that person may think the Marxist means "surplus" in the sense of "unnecessary excess". They may think the Marxist means that the worker's productivity is wasted, and respond accordingly. This may baffle the Marxist, who will point out that "surplus value" (in their sense) doesn't have much to do with "overproduction" (another word that has a specific meaning in Marxist economics).
Using neologisms has the advantage that it conveys readily, to someone unfamiliar with the neologism, that they are unfamiliar with it and need to ask for clarification. Using existing words with unusually precise meanings runs the risk of letting someone go past a misunderstood word without realizing that they are doing so.
I don't think jkaufman meant we should use familiar-sounding words with unfamiliar overly precise meanings, but rather that we shouldn't get in the habit of using unfamiliar overly precise concepts even when we don't really need to (“unfamiliar” here meaning ‘unfamiliar to most audiences’, not ‘unfamiliar to the speaker’, of course).
When a group of people talk to each other a lot they develop terms that they can use in place of larger concepts. This makes it easier to talk to people inside the group, but then it's harder to talk about the same ideas with people outside the group. If we were smart enough to keep up fully independent vocabularies where we would always use the right words for the people we were talking to, this wouldn't be an issue. But instead we get in the habit of saying weird words, and then when we want to talk to people who don't know those words we either struggle to find words they know or waste a lot of time introducing words. Especially when the group jargon term offers only a minor advantage over the non-jargon phrasing I think this is a bad tradeoff if you also want to speak to people outside the group.
Recently I've been working on using as little jargon as possible. Pushing myself to speak conventionally, even when among people who would understand weird terms a little faster, can be frustrating, but I think I'm also getting better at it.
I also posted this on my blog