Why do topic titles need to be unique?

I have 2 guesses as to why.

  1. To prevent spam. This would make it hard for spammers to just name their topics Go to <Some scam website> for 5 bitcoin. They would need to at least add an extra character.
  2. To make people be more creative and help with the search. So instead of I am having trouble with x topic 5 times you would need to explain in more detail what your problem is in the title.