Using your fandom blog as a personal one, why?

I follow a few fandom blogs on tumblr, but they also trow in non-fandom related posts, like talking about their boy/girlfriends, how much they love them or what they are doing right now.
They have a personal blog, I follow them on there as well, but those are pretty much dead since they trow all of their personal posts on their fandom blogs.
Really, using your fandom blog as a personal one just because it has more followers so more peeps see your non fandom related posts that aren't even really that important?
I understand if you're talking about a sick pet that you can donate money for if you can't pay the vet yourself and stuff like that, but talking about random stuf that doesn't even have anything to do with the fandom on that blog?
Why do you do that? That is really super annoying if you got a personal one to do that on.
Talking about things that aren't related to your fandom blog, kinda defeats the purpose of calling it a 'fan-dom blog'
I know, it's your blog and you can do whatever you want on it, I just find it annoying and the defeats the purpose of having your own blog.

That's my opinion.