It’s a little dense but this article explains a lot.
Your explanation is most correct. In analog (NTSC) video, once the first line is scanned, the next line to be scanned is actually line 3 (not line 2). This goes on scanning every odd line until the bottom of the screen. At this point, back at the top of the picture, the even lines are displayed and interlaces with the odd lines. This is where the concept of interlaces TV is formed. All of the odd lines are displayed and in the next 1/60th of a second the even lines are displayed forming a full raster in 1/3oth of a second-for NTSC. PAL is a bit different but similar. ATSC TV is different. Here the blanking intervals are needed mostly for proper timing of the signals and not necessarily for the blanking of the electron beam within the receiver. It’s important in the timing of the transmission signals and in the decoder of an ATSC receiver. Same timing but different reasons.
Not my monkeys. Not my circus.