Yes, because the scan frequency didn't change -- that's what I'm trying to say (my terminology may have been a bit off). The timings of the horizontal and vertical sweep of the beam were constant; upon mode change the CRTC changed how scanout occurred, doubling the width or height of pixels in lower resolution mode but it didn't change the scan frequency, allowing the mode change to occur while the beam kept moving along.

PC monitors were analog too, but with PC monitors from EGA onwards, changing modes meant potentially changing scan frequency, which required the monitor to sync with the signal at the new frequency. Apparently a high-quality Sony monitor could do this instantly but many of us were slumming it with monitors that took a while to sync.