It also makes it more accessible if the language is consistent. I remember when I learned the reddit-specific terms like sub, subreddit, redditor, OP and so on. They seem obvious in hindsight, but some of them were not when I had no idea. Now imagine for each term, there would be multiple synonyms. The feeling of “I have no firm understanding of what they are talking about” would last longer, which isn’t exactly a pleasant experience for newcomers.