I think-- to some degree-- this is the result of Steemit not really being a "click for cash" site, but rather a social blogging/social content site that just happens to pay out rewards.

In other words, the focus here is heavily on "community building," which is also why we see so many posts encouraging people to "power up" rather than cash out.

To answer your question of "Do we just not want those folks here?" I expect many would have reservations. Why? Because the Steemit mission seems to be focused around helping people become "stake holders" in the community being created. Someone who comes in here and makes a bunch of posts and cashes out every time they have $5 really don't help the platform, in the long run. How so? Because they don't really care about "the content," they care about "the cash" only. In fact, it's that very mindset that causes the consistent demise of sites MyLot (you mentioned it) which had to suspend payments; Bubblews, the biggest screwup of all time, Tsu and others.

Also, part of the mission here is to make Steem-- the alt coin-- an actual and viable form of payment for goods and services... and if it's too easy for people to turn their Steem into Dollars every three minutes, that's never going to happen.

So, when we think of "mainstream," what's really suggested (just my take-- keep in mind I've only been here for six weeks, myself!) is perhaps "the 1% MOST alternative, anarchist, independent, Libertarian, Freethinker people on Facebook." Which would still be 25 million people... a pretty "stout" niche.

But hey, I'm no expert... I'd love to see some of the old timers chime in, here.