Curmudgeons don’t handle change well. Nor do they handle newbies well—unless of course newbies do it the way we always did it. Curmudgeons aren’t known for their civility!
It’s also not at all welcoming to say “We’ve talked about this before” and provide only links to other threads. It shuts a person down. It also has an “I know better than you” air about it. And it doesn’t take whoever took the time to post something seriously enough to engage what they posted, but does take them seriously enough to effectively say, “Shut up.” It also breeds an in-group/out-group cliquish culture. Although some are okay with that—when they’re part of the in-group.
What exactly is gained by wading into a discussion and saying, “We’ve talked about this before?” Who benefits from that? The OP certainly not. Perhaps the one making the remark, but likely at the expense of someone else. Again—hardly civil behavior!