From time to time, when I go through the "Low quality posts" review queue, I come across link-only answers that has accumulated multiple "Recommend Deletion" votes.
An example from today is the answer from Cypher to this one: theme_key does not switch theme when URL user/<uid>/edit is called
While the answer was indeed link-only when it entered the queue (I've tried to remedy that), the original answer was not completely worthless. As it stood, it would help future visitors solve the problem unless the link had died.
This is what the help center has to say on the subject:
Links to external resources are encouraged, but please add context around the link so your fellow users will have some idea what it is and why it’s there. Always quote the most relevant part of an important link, in case the target site is unreachable or goes permanently offline.
If you think that a downright quote will be a copyright violation, consider summarising or paraphrasing instead. Facts can't be copyrighted (only the way they're presented are), so summarising or paraphrasing a factual statement will never be a copyright violation.
It usually just takes a few seconds of copy-pasting from the source to transform a link-only answer from one that will become useless when the link goes dead, to one whose usefulness no longer shall depend on the link working.
Please do not just vote to delete these. Take the time to salvage them instead.