DS doesn't always mean Dear Son or Darling Sister. Very often Sometimes it means Dratted Sister or Damned Son.
If everyone typed with one finger as slowly as I do, they would have to use accepted abbreviations or they wouldn't get the message posted until the conversation had moved on to a completely different subject.
Do you type British Broadcasting Corporation Channel 2 whenever you want to mention BBC2 ?
Our Welfare State. Is it broken?