I'm interested to hear arguments banning the ability to create your own title.
I did not mention I want to ban the ability to create your own title.
There are legitimate reasons to create your own title:
  • Article title is too long
  • Article has no title
  • Article title can't be parsed
  • Article title is bad (not descriptive enough; wrong etc.)
  • ... ???
The HN guidelines also mention this regarding not using the original title:
If the title contains a gratuitous number or number + adjective, we'd appreciate it if you'd crop it. E.g. translate "10 Ways To Do X" to "How To Do X," and "14 Amazing Ys" to "Ys." Exception: when the number is meaningful, e.g. "The 5 Platonic Solids."
However:
Otherwise please use the original title, unless it is misleading or linkbait; don't editorialize.