Fair enough, but mistake or not, you are asking many questions about the article.
A broad enough for what purpose? I will tell you, for my purpose, S&S addresses _more_ than I need, not less. I'm perfectly happy deadlifting and walking. If you'll forgive me, I will take some examples from my career as a musician and music teacher.
You can hand me most kinds of music, in styles I've never even heard of, and I will play it well enough that you'll say, "Yes, that's exactly how it goes - how did you know?" I know because I have prepared myself by methods that make me an anti-fragile musician - I can play anything someone has written down correctly, and I can figure out just about everything by ear if it's not written down.
I teach my students according to the same philosophy: I teach them to how fish rather than handing them one fish. I prepare them for whatever may come their way and whatever they may wish to do with their skills for the rest of their lives.
S&S is such a program - on it, you can build may kinds of specific fitness, but S&S makes no attempt to be "broad spectrum" in its choice of movements. To the contrary, S&S states, and I agree 110%, that most people will be better off, and most goals better achieved, by achieving a high level of skill in a few, basic movements. A "broad spectrum" of people will benefit from S&S's very limited but highly focused choice of exercises.
Why? One can incorporate other moves when there are reasons to do so. I practice swings and getups, and deadlifts and one-armed pushups and overhead presses. The first two are foundational movements as explained in S&S, and they help me with the other three, which are movements I want to be better at in competition and/or for my own satisfaction.
What "effect" are you looking for?
S&S is enough to build a good foundation, and if it's enough to build a good foundation, what more does one need? Can you build a better foundation? A foundation's purpose is to support what you build on it; if your foundation does that, what purpose is served by having a "better" foundation? If your goals require specific things, let's address those issues specifically. A foundation is, by definition, general.
Is more better? Sometimes, yes, and sometimes, no. All we can say about more is that it's more. All we can say about S&S is that we have a long thread in "I Achieved Simple and Here's My Story," full of people telling us how S&S has improved their strength, their endurance, their martial arts performance, and a whole host of other things. One can build many kinds of house on the same foundation.
Yes.
Clearer now?
-S-