There was a good few years where you could make an entire career out of re-hashing Java blog posts from 2000-2005 with Ruby syntax and be considered on the cutting edge. I should know; my first blog post was about dependency injection in Ruby. This was especially ironic given how long Rubyists shit-talked Java all those years.

There's a few things at play here: it's true, to many people, the last ten years didn't exist! There are a ton of programmers who have less than ten years in the industry. It takes time to learn all that history. Another aspect is that teaching something you've just learned to others is a great way to solidify your knowledge of that thing. You also have https://xkcd.com/1053/