Blog owner here. You're welcome to unblur it: I swapped the number out in the screenshot for one of Ofcom's list of official never-to-be-assigned telephone numbers for drama (e.g. film & TV) use (https://www.ofcom.org.uk/phones-and-broadband/phone-numbers/...) before I applied the blur.
That number isn't mine, and will never belong to anybody!
Blurring makes sense as a way to say "this is private". It's almost lampshading, in this case, because it's the bit I want you to look at!
But blurring doesn't make sense from a privacy perspective, because unblurring is pretty easy. So I modified the number to a known-fake, will-never-be-valid one.
But if I just did that, people would probably try to call it, or would say "but you've put it back online here", or similar. Or else would say "that number's fake anyway, why are you worried?". Blurring it as well achieved the best of all worlds: it lampshades the bit I'm talking about, and it indicates that the kind of data stored there should be considered private, and it prevents the actual extraction of the (real) private data from the image. Win, win, win.
Unless the question "why bother" was to imply that blurring was hard to do? Because it definitely wasn't. Changing the number took much more effort! The blur was just two clicks; significantly less effort than, say, explaining why I chose to do so! :-D
Often I'm lazy and just black out revealing information, like I did in my blog post about how British Gas can't understand my name (https://danq.me/it-is-only-q).
But sometimes I've done the same thing in other places and gone further, sometimes concealing "fun" messages. In my post about Halifax putting the wrong names on a letter to me (https://danq.me/halifax-dun-goofed), I changed my address to a message along the lines of "what, you think I'd put my actual address here, like it's my first day on the Internet" and then blurred that.
Incidentally, I think that one was the first times that anybody contacted me to say that they'd noticed the unblurrability of my images, but I've been using this approach for years!
That number isn't mine, and will never belong to anybody!