I don't find any benefit for programmers to promote their work via blog posts.
There are plenty of forums and platforms dedicated to the programming community where programmers are able to post their work or improve the code of others and gain publicity...
Agreed. I can imagine a website where you post some of your code as a portfolio when you're looking for a job... wait for a second! There already are hundreds of websites like this. I don't want to be a killjoy but this blog doesn't have a huge potential.
I want my blog posts to be more personal, like real blog posts, not just GitHub. Also, a blog posts where you actually have a form of conversation with the audience, not just plain copy-paste of code. A place where you can show what you are interested in, what have you been doing, what are some of your views on certain things, what are your plans for the future etc.
Also, could you, please, share some of the websites you are thinking of?