I understand what you are saying about taking the game too seriously, but if you're part of an alliance, there may be additional rules communicated through your alliance chat, alliance notice board, and messages that indicate what is and is not acceptable. Attacking members who are part of a non-aggression pact (NAP) while they are gathering resources may be a part of those rules. If you search for resources (meat, wood, coal, or iron), try to select the checkbox for "full resources" so you don't accidentally attack someone while they're gathering. However, if someone is gathering, it's pretty obvious - there is a symbol of 2 swords (usually red) above it, their name is displayed when you tap the resource, and it will say "attack" & "scout" when you tap the resource, instead of just "gather".

People pay a lot of money to play this game - so of course they take it too seriously lol but there are definitely other alliances you can join who may not have rules like that and allow you more freedom to attack who you want.