The mention about intent is pretty much correct here.
It is not inherently wrong to take camps. But it is if it is causing your team to be behind or not be able to play properly.
There are specifics in the TOS about playing in ways that hinder your team or hurt their chances.
KDA Umbra goes over that pretty well with the examples.
If you get to late game and everything is on fire (so to speak) and you are farming Krugs because it is unsafe to go out and get farm and the JG complains... That is probably more of a "them" thing to be honest. But it is better to talk something over with your team rather than just mess up their JG pathing and such.
Something to consider is if someone is one camp away from buying an item and you steal that camp and they cannot reasonably go get more gold and cannot afford to go back then go back again after another camp because of an objective timing, you are actively hindering them without knowing it. Only they know it. This happens a lot when a JG comes into lane and steals CS. It can mess up your wave control and can destroy your item timing backs. Technically, this is griefing because it actively hinders your team. It is unlikely to be punished because the automated system cannot really check for it but if a bunch of reports come from a lot of games probably.
A human could easily enough determine if this was griefing or merely bad play though. In general, if in doubt, just ask.
That is why I am rarely happy playing with a random for JG. Stealing CS and not getting "my" blue buff. :/