It’s critical if you’re an independent contractor or will become one some day. Writing blog posts about interesting projects or topics then submitting them to tech news aggregators (HN, lobste.rs, r/programming) pays dividends for years. Not even from the post itself necessarily, but it ensures you show up in search results. Much easier than writing a textbook, doing conf talks, or building a really good network. Plus it’s also nice on a psychological level, I feel I only get closure on projects once I write about them.