In what way do you think the requirement that signals be viewable on black and white televisions impaired the technology? While there are certainly other possible encoding methods, the only ones I can think of that wouldn't be compatible with black and white sets would have required too much circuitry to be practical in a consumer-level product in the vacuum-tube era (Betacam splits a color signal into YUV components, then on each scan line it outputs Y at double-speed, followed by U at quad-speed and V at quad-speed; excellent method, but I don't know how to handle the conversion without using an analog shift register or other such buffering device).
The NTSC toob type color TVs all had a delay line in their circuitry, though the delay was much less than a scan line's worth of signal. It was put in the signal path for the monochrome video (Y) because the narrower bandwidth of the color signal path introduced its own delay. The monochrome had to be slowed down so that the color and monochrome video would arrive at the picture tube in proper sync. Having the color signals transmit twice as fast as the monochrome signal would pose a problem, but if all occupied the same width of time slot then the design would be trivial using delay lines.