I just want to expand on this a bit, using an example that doesn't involve any gray areas of the TOS.
1. Some groups will want you to have full crafted, max meld gear for raiding on day one, or as close to day one as possible.
2. Others will go "What's the point of wasting that much money on stuff that will quickly be replaced anyways."
People with #2 mentality joining a #1 kind of group will have problems. They'll resent having to spend so much money (or hours on DoH/L). Conversely, the group will resent the joiner for not adequately preparing. And vice-versa, someone with the #1 mentality joining a #2 kind of group won't be happy with the group not taking it seriously enough, or whatever else.
There's many other metrics but in short, it's pretty important to join a group with similar expectations to your own. That can be a no parse group if you wish, they do exist. Or any number of other things that some people consider important to do a certain way, and can cause friction/resentment when those expectations aren't met.
