Only if you want to play the SEO game, which is a very different game from publishing on blogging platforms and social media sites that all come with a huge built-in audience.

You see, SEO matters a lot if you have a blog of your own that no one knows. In that case, there simply isn't any audience you can tap into. You just have your lonely wordpress blog (or whatever) in some corner of the Internet and no one knows about it. So the only way to really drive traffic in that case to your blog is SEO. After all, posting links to your blog on social media doesn't really work because all social media sites want to keep their users within their walled garden and so they will not promote any posts that take their users elsewhere.

But if you're on a platform that has an audience, SEO is usually unnecessary and often just a waste of time.

Think of it this way. Publishing on your own blog is like setting up a little shop in the desert and then trying to get people to visit you. Here SEO matters.

But publishing on a platform is like setting up a little shop in a huge buzzing mall full of millions of people. SEO is like trying to bring people to your little shop who are out on the street. You can of course do that, but what's the point if there are already so many people within the mall? Just appeal to the people who are already within the mall and stop focusing on the ones outside of it!