[Dan-Q]

To indicate to the reader that the information represented by this area of the image should be considered private.

It's like how they blur nipples on TV. We all know what nipples look like! But they're blurred to say "yeah, but maybe you shouldn't be looking".

[saretup]

That serves a purpose. This is more like choosing abstinence as a form of birth control but wearing a condom anyway.

[Dan-Q]

Yeah, it was a bad metaphor. I was sleepy.

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