  La$_{1.67}$Sr$_{0.33}$CuO$_4$ is not a superconductor and its resistivity
follows a purely T$^2$ temperature dependence at very low temperatures.
La$_{1.71}$Sr$_{0.29}$CuO$_4$, on the other hand, has a superconducting ground
state together with a T-Linear term in its resistivity. The concomitant
emergence of these two features below a critical doping is mystifying. Here, I
notice that the electron-electron collision rate in the Fermi liquid above the
doping threshold is unusually large. The scattering time of nodal
quasi-particles expressed in a dimensionless parameter $\zeta$ is very close to
what has been found in liquid $^3$He at its melting pressure. In the latter
case, fermionic particles become dynamically distinguishable by excess of
interaction. Ceasing to be dynamically indistinguishable, nodal electrons will
be excluded from the Fermi sea. Such non-degenerate carriers will then scatter
the degenerate ones within a phase space growing linearly with temperature.
