Should is a word “used to indicate obligation, duty, or correctness” (thank you Webster). Telling another adult what they should or should not have to do is pretty darned bossy (as in domineering, overbearing, officious, take you pick).

Should is also used, a lot, by bullies (as in tyrants, aggressors, and persecutors).

Should is also a word used by immature people who lack experience and confidence in themselves. By the time you turn 21, its a good idea to remove should from your vocabulary.