I'm not entirely convinced this is true. Our first eleven is good in some areas, lacking in others.
Areas of strength - striker (Harry), attacking midfielders (Eriksen/Alli/Son or Lucas), CB (Sanchez + Verts), in goal (Hugo). There are still a couple of weak-ish spots here, mind (Son's availability and form might seriously fluctuate this year, and Sanchez is still a bit raw and needs a rest after three straight years of football without a break).
Passable areas - right-back (Trippier or Aurier). Both can be superb on their day, although with Aurier those days haven't yet been frequent, and in Trippier's case, those days have been balanced out with days where he's been skinned and left for dead by wingers with pace and skill (Sane, Martial, Sanchez et al).
Weak areas - left back, central midfield.
Left back - Davies is solid, but not superb. Rose was superb in 16/17, but has had an annus horribilis, England exploits aside.
Central midfield - Dier is a dependable (if unspectacular) defensive midfielder, but Wanyama looked well off the pace upon his return back in March/April. It's even worse with the other two options - Dembele started showing his age at multiple points last season, and Winks isn't ready yet given the stalling of his progress due to that injury he's been nursing for eight-odd months.
Thus, I don't think we're quite as strong as to necessitate this sort of surgical precision in our signings. Our first eleven has definite spaces for improvement.