Let me give you an example.
Suppose that you want to discuss a really controversial topic. Each platform has its own “guidelines,” as they call them - they really amount to a list of rules. They tell you what you can write about, and what you can't. They tell you how long, or how short your posts can be. They tell you what you can put in your resource box too. And many, if not most, have absolutely no place at all for people to interact with you. In other words, there's no place for comments.
When you have your own blog, you make your own rules. I can tell you - as a seasoned internet marketer that I still have articles that are rejected because they violate the guidelines of one person or another in a directory. I find that really annoying. I know that I write high quality content. It's a waste of my time to submit it somewhere only to have some minimum wage neophyte reject it over a technicality.
Having my own blog makes that irrelevant. It doesn't mean that I won't use the other platforms, but it does mean that I have more control over the content I create. The only thing that could cause a problem is if what I had to say was so bad that my web host closed my site – and that’s not something I’m planning to have happen!
With your blog, you can say what you feel needs to be said.
You also get to decide when it will be published. I mentioned already that when an article gets rejected it wastes my time. One reason for that is that there isn't enough information given by that platform to tell me what the problem is. So I have to write to them, grovel a bit, and then wait for them to reply. I once had a problem that lasted for 2 weeks. Nothing got published during that time. If I had a blog, it wouldn't have mattered. The same thing is true for you. No matter what the policies are for someone else, you can just keep cranking out your posts day in and day out.
You can also decide where to put your content on your blog. If you write for an article directory, for example, it appears along with the content of thousands of other people. But if it's on your blog, it's just you. And, you can put it anywhere you want to.
If you use guest bloggers, the fact that they write for you just adds to your credibility as an expert.
So your strategy has to be to get your prospects from the search engine results to your blog so that they can read, watch, or listen to the high quality information you have for them. That's so that they will join your list and eventually buy the life changing products that you've created to help them solve their problems.
That's the foundation, everything is built on that, everything.
On the one hand you have to get your expertise in front of your prospects. But on the other your expertise has to draw them to your blog so that they can discover for themselves that you're the expert they need.