- The original blog was deleted, by the owner, or by Blogger anti-splog efforts.
- The owner switched to external publishing, or to a new URL, and did not plan the change properly.
- The owner did not practise proper security.
- The owner made no mistake. The attack came thru Blogger / Blogspot security.
One of the problems with the above list is that nobody knows if it's complete. Nobody really knows what is happening. All we can do is report the problem to Blogger Support. Sometimes, Blogger Support can resolve the immediate issue - the individual hijacked blog. But they have yet to report back, and let us know what the hell is going on.
The individual blog owners don't help a lot either. They see the problem, they report the problem, the problem is fixed (their problem is fixed), they go back to blogging.
If you know anything, and aren't telling what you know, then you are part of the problem.
If you know anything about the above issues, and are not writing about them, then you are part of the problem. If you are one of those directly affected, then you are obviously part of the problem. If you have a blog, you may be part of the problem; until this is solved, you may become part of the problem at any time.
The solution to the problem begins with you.