Could you expand on this. If someone is using words not in the top 10,000 words along with words in the top 10,000, and they pick 4-5 words, how is semantic net

Could you expand on this. If someone is using words not in the top 10,000 words along with words in the top 10,000, and they pick 4-5 words, how is semantic network analysis going to help? You're saying this analysis can reduce the ~10,000 possibilities to something much smaller? And you're reasoning being that people don't actually pick from the top 10,000? How does that work?