Background: In many error correction codes in particular the surface code, the Clifford operations generated by the S,H and CNOT are transversal for quantum computation (meaning that these logical gates can be implemented in easily with very low circuit depth).
However, the Eastin-Knill theorem tells us that one can never get a universal gate set transversally. Whenever the Clifford gates are transversal, such as for the important example of the surface code, the gate the is considered to make the gate set universal is usually the T gate
$$T = \begin{pmatrix} 1 & 0 \\ 0 & e^{i \frac{\pi}{4}} \end{pmatrix}, $$ which is a single qubit rotation. The $T$ gates are then usually implemented using T-states and T-state distillation
QuestionThe T-gate and counting T states is so common that we have the Clifford+T paradigm. But why the focus on $T$ gates? Most rotation gates would complete the gate set to a universal set. Is it because it is "furthest" away from Clifford?