It is not really about saving one oscillator, but about two things:
- saving the drive circuitry for the flyback, which is usually combined with horizontal deflection amplifier. Also such a design probably simplifies the output filter for horizontal deflection as the flyback primary is part of that filter.
- synchronizing the main PSU of the display to the horizontal sync as to make various interference artifacts in the image stay in place instead of slowly vandering around, which will make them more distracting and noticable.
It is not that hard to see the whole CRT monitor as essentially being one giant SMPS that produces bunch of really weird voltages with weird waveforms. And in fact is you take apart mid-90's CRT display (without OSD), the actual video circuitry is one IC, few passives and lot of overvoltage protection, rest of the thing is powersupply and the deflection drivers (which are kind of also an power supply, as the required currents are significant).
- saving the drive circuitry for the flyback, which is usually combined with horizontal deflection amplifier. Also such a design probably simplifies the output filter for horizontal deflection as the flyback primary is part of that filter.
- synchronizing the main PSU of the display to the horizontal sync as to make various interference artifacts in the image stay in place instead of slowly vandering around, which will make them more distracting and noticable.
It is not that hard to see the whole CRT monitor as essentially being one giant SMPS that produces bunch of really weird voltages with weird waveforms. And in fact is you take apart mid-90's CRT display (without OSD), the actual video circuitry is one IC, few passives and lot of overvoltage protection, rest of the thing is powersupply and the deflection drivers (which are kind of also an power supply, as the required currents are significant).