It's inconsiderate of others to write/say things in a way that requires the other person to spend unreasonable amounts of time and effort figuring out what the

It's inconsiderate of others to write/say things in a way that requires the other person to spend unreasonable amounts of time and effort figuring out what the hell you're talking about. Some people just don't care about being considerate, so they don't bother. It's the same sort of thing as using clean dishes in the break room and not washing them afterward. You save yourself time and effort at the expense of making someone else do it. Actually, it's probably worse than that. The writer might save 30 seconds at the expense of forcing the reader to spend 5 minutes puzzling out what they meant. Or, if an email has wide distribution, 1 minute saved for the writer might result in wasting 30 seconds for 100 people.