I think there's a selection bias involved in your analysis. There has long been a tendency towards teams focused on ATH/SPD/DEF, and after aejones posted his Guide to Winning at D2 and D3 it got much, much worse. Everybody is pretty convinced that this is the way to win. It's certainly an easy way to win a lot. Building a great, efficient offense requires a lot of parts that fit together and have to recycle at a steady rate (IE when your PG graduates, you need to have a new PG ready to step up). Maintaining a great defense is easy. There is the added benefit that ATH and SPD make guys reasonably effective interior scorers. So a great defensive team is generally at least a decent offensive team. The reverse is less certain to be true. And now, with most of the worlds at most levels experiencing all-time low human coach populations, it's pretty easy for everybody to adopt the same basic strategy. When there were 400+ human coaches in a world, everybody couldn't have a team with elite ATH/SPD. There wasn't enough to go around. With current populations, there generally is.
But it is still entirely possible to win with a team built on offensive efficiency and without elite defense. Look at my Methodist team. We just went to the title game. We have 0 walk-ons. Even so, my team is 24th in D3 in team ATH and 18th in DEF. And while those numbers sound good out of 384 D3 teams, consider that Tark has 48 human coaches. Without looking closely, I'd say that it's a good bet that fewer than 40 teams exist comprised entirely of human-recruited players. So by that standard, compared to comparable teams, my team is pretty middle-of-the-pack in athleticism and defense. What we are, however, was the clear-cut best shooting team in D3, with 4 players with 91+ PER. My team BH and Pass were 4th and 8th, respectively. We didn't turn the ball over. We shot efficiently. I also was in the discussion for best-rebounding team in D3 - not by REB rating, since we were only 4 deep in post players, but in terms of the guys on the floor at any given time we could compete on the boards with any other team in D3.
The problem, as I alluded to above, is that running a team like this is harder to maintain. I prefer to be opportunistic in recruiting and take the best available guys, but it's not always possible. Of my 4 posts, 1 is graduating now and 2 more go next year. The elite post I was recruiting wound up going to a Big 6 school (where he didn't belong, with a cap of low-70s ATH), so now I only am likely to replace the guy I'm losing. That means that next recruiting cycle I really need to bring in 2 post players. Doesn't matter if I find guys I really like. I need to fill those spots. I also had to recruit Barnoski, who is never going to be an adequate defender, because I need a PG starting next season, and he was the best available guy to fill that need. A solid passer at the 1 makes a real difference when your strategy for winning is dependent on efficient 3 point shooting. If you look at my team performance since the HD3 rollout, you'll note that my teams have not been very consistent.
But the key point here is that when the elements come together, it is entirely possible to win at this game in more than 1 way. It should be pointed out that a certain threshold of defensive proficiency has to always be met. You can't be deficient. But you can win with average defense and elite scoring.