We definitely have a lot more Lunatic players than we have in the past. Back in say 2007~2008, there were barely any on MotK or other western communities because most were just getting into the series. Coming up to UFO more got to that level (cue "UFO Lunatic is impossible"), but ever since around 2010 I think we've exploded in the number of members who are Lunatic players. And because people don't just leave, we then have an ever-increasing number of Lunatics. Because they like it here and play a lot, they post often, and the board seems to fill up with their posts, leading to the point where people look in and go "wow there are so many Lunatic players". I would really like HME to become dominated with newer players, I think that's a healthy state for the board to be in.
I don't think it's good for people to assume Lunatic unless stated otherwise. If a particular member is known to play at a given difficulty or posts often, it might be clear to others what difficulty they play on. But just because these people post a lot shouldn't mean Lunatic should be the default. I don't think that affords a healthy environment for other players at all; saying that Lunatic is pretty much what everyone plays on does create the problem where people playing on lower difficulties do start comparing themselves to what is said to be a standard.
Where I would say that Lunatic would be "standard" is with things like advice on how to tackle patterns. In most cases, advice for Lunatic applies pretty much the same across all difficulties (or it's pointless advice like needing extra movements), and often times how to do a pattern on Lunatic informs easier ways to do it on lower difficulties. Pattern design and structure becomes more obvious when considering Lunatic. These sorts of things.