Kwello,
You can have a smaller, but still complete, physique with a 300lb bench/squat/deadlift. You missed the point, which was that doing the basic compound exercises will fill out EVERY part of your physique without a need for isolating stuff like rear delts, traps, neck etc.
If you have a strong bench, are you JUST gonna have a strong/big chest? No, you'll have big shoulders, big triceps, big lats, big traps - all of these are involved in benching and progressive
And you're saying that the adductors/abductors don't get worked if you squat? What do you think keeps the knees from coming in?
Same with traps/rear delts. Look at the strongest deadlifters in the world, do they have small traps or necks?
Concentrate on getting the basic lifts to a point which equals the size you want. Having a 300/400/500 may not be big enough for you, and you'd need to get to 400/500/600. Or maybe just getting 200/300/400 is enough for you, it doesn't matter. You can do as much isolation work as you want but your progress will always be proportionate to your total.
Maybe some guys will need extra isolation work to work on a weak point BUT unless you already have a significant strength and muscular base (different for every person), your whole BODY is a weak point - you can't tell me for example that a 150lb guy needs extra work on his rear delts or 'upper inner outer chest'.