Definitely we can write about anything, there is a lot of things we experience every day that can translate into a post. I think many people think that not all of that can be interesting enough, some people are waiting for a great theme to write about, I can undestand that because not all of us have a faithful base of followers willing to read each mundane post we put out there, but I know that in theory we can write about many things.
someone said to me a long time ago, that there is absolutely no way that everyone can like you... i think accepting that is liberating. I've been called a shitposter, so what? I enjoy writing, and I will continue to do so.