The original 1953 NTSC standard specified phosphors with a way bigger gamut than sRGB, that were chosen to approximate the gamut of film projectors.

Original NTSC cyans are more saturated than even DCI-P3 cyans.

Typical CRTs use the cheaper, brighter phosphors specified by SMPTE C (the basis for the sRGB gamut) and a circuit that pumps the saturation to compensate.

It's likely your screen uses the better phosphors instead of a colour correction circuit.