All of those questions you cite are 4 years old.

They were acceptable then.

Now, if they were asked, they'd likely be closed as a duplicate, or as requiring minimum effort.

Those questions are still open simply because they haven't been closed by the community. It only takes 5 votes.

[Even your own question][1] you cite(!) is still written well enough to 'get around' that requirement.  It's got a good answer, it isn't a glaring eyesore, so it's still open.  

If the community wants to close it, they can always vote to close it. If you want it closed, you can always flag it for closure, and it'll be put into the review queue. If the community agrees with you, it'll be closed.


  [1]: http://stackoverflow.com/questions/14670632/algorithm-to-find-the-most-common-substrings-in-a-string