I suggested 5 reps for a reason. The reason being that getting bigger requires getting stronger. In addition, 5 reps builds a bit strength while also providing sufficient stimulus to force growth. It is most useful to build a strength base first and then transition to higher reps if looks are the goal. Also, all other things being equal the stronger athlete is the better athlete regardless of who is bigger.
If you actually read what I wrote, you'll see that I suggested 5 reps for the compound movements and higher reps of 10- 12 for the isolation work. The isolation work is to give the muscles hit by the compound movement more volume and to help promote growth
Yes form is important, but perfect is the enemy of good in this situation. Adding weight at constant intervals is the basis of progressive overload, something that is essential for progress. Getting bigger and stronger is like getting a sun tan, you must continually provide more stimulus in order to force the body to adapt. As a newb, one can adapt to the stimulus from one workout in 24-48 hours and in order to force further adaptation, more weight must be added with each session.
How is it going to be hard to follow? You don't squat every day, you squat every legs or lower day which is 1-2x a week, completely doable. Furthermore, you won't be deadlifting every day either since you only do it on pull day which means its again 1-2x a week...something entirely doable for a newb.
Next, yes the deadlift does work the legs, however, it is NOT a leg dominant exercise. When properly performed, a deadlift mainly targets the muscles of the back as well, namely the spinal erectors which must maintain the spinal extension throughout the pull.
Finally, hitting all the muscle groups as quickly as possible is horribly inefficient for someone who has little training experience. Furthermore, how does one hit all the muscle groups as quickly as possible without doing 17 different exercises which, IMO, is a grand waste of time unless you are going to compete in bodybuilding.