  There are two commonly discussed points of view in theoretical description of
cuprate superconductors, (i) Cuprates can be described by the modified t-J
model. (ii) Overdoped cuprates are close to the regime of normal Fermi liquid
(NFL). We argue that recent resonant inelastic X-ray scattering data challenge
both points. While the modified t-J model describes well the strongly
underdoped regime, it fails to describe high energy magnetic excitations when
approaching optimal doping. This probably indicates failure of the Zhang-Rice
singlet picture. In the overdoped regime the momentum-integrated spin structure
factor S(\omega) has the same intensity and energy distribution as that in an
undoped parent compound. This implies that the entire spin spectral sum rule is
saturated at \omega ~ 2J, while in a NFL the spectral weight should saturate
only at the total bandwidth which is much larger than 2J.
