Doesn't strike me as true, 50 fps video is very common all over the world and doesn't have many issues besides noticeable flicker on CRTs.
Note that 24 fps film cinema runs at 72 Hz flicker due to triple-exposing each frame. That's why they could get away with 24 fps: Since they are dealing with stored images, multiple exposures were possible to avoid flickering. Using as low fps as possible was desirable because film costs money, film transports get more finicky as fps are increased and exposure gets tricky (doubling or even tripling the frame rate leaves you with a much shorter exposure time, which you need to compensate either with a larger aperture (which may not be available, or if it is, cost a lot of money), or more sensitive film (which may not have been available, or has much worse quality), or by having more light in the scene -- all of these are either undesirable or expensive).
So they chose 24 fps because the motion perception isn't quite in the shitter at that fps, though it's pretty bad (nowadays idolized as "cinematic look"; even more hip and cool if you do it on Youtube and deliver 24p which gets converted to 60 fps by means of 3:2 alternation, resulting in a super janky look known as "That Pro Youtuber Look"). This is the reason why people did not like The Hobbit.
Meanwhile video people went on to invent interlacing, because video was fundamentally about a non-stored image. Here the reason why low fps are desirable are again cost, since higher fps needs higher video bandwidth, and that makes everything more expensive and lets you have fewer channels (likely not a concern in the early days). Interlacing lets you have a higher frame rate (a CRT at 25 Hz or even 30 Hz will trigger nausea in everyone) without incurring higher costs, just like multiple exposures in a cinema projector.
Note that 24 fps film cinema runs at 72 Hz flicker due to triple-exposing each frame. That's why they could get away with 24 fps: Since they are dealing with stored images, multiple exposures were possible to avoid flickering. Using as low fps as possible was desirable because film costs money, film transports get more finicky as fps are increased and exposure gets tricky (doubling or even tripling the frame rate leaves you with a much shorter exposure time, which you need to compensate either with a larger aperture (which may not be available, or if it is, cost a lot of money), or more sensitive film (which may not have been available, or has much worse quality), or by having more light in the scene -- all of these are either undesirable or expensive).
So they chose 24 fps because the motion perception isn't quite in the shitter at that fps, though it's pretty bad (nowadays idolized as "cinematic look"; even more hip and cool if you do it on Youtube and deliver 24p which gets converted to 60 fps by means of 3:2 alternation, resulting in a super janky look known as "That Pro Youtuber Look"). This is the reason why people did not like The Hobbit.
Meanwhile video people went on to invent interlacing, because video was fundamentally about a non-stored image. Here the reason why low fps are desirable are again cost, since higher fps needs higher video bandwidth, and that makes everything more expensive and lets you have fewer channels (likely not a concern in the early days). Interlacing lets you have a higher frame rate (a CRT at 25 Hz or even 30 Hz will trigger nausea in everyone) without incurring higher costs, just like multiple exposures in a cinema projector.