Is It the Right Idea to Learn How to Do Things Yourself?

I was watching a YouTube of Jason Cohen from Smart Bear and WP Engine. He said it's the wrong idea to try and learn how to do stuff yourself. I thought that could be an efficient way, right? You can't get good at everything. It's all in your head. That's core you're doing. The more you divide up really essential pieces of what you're doing then it just helps make a lot more progress. But things like SEO,  it's not that complicated. Like how close is it to your wheelhouse? Yeah.