This has a grain of truth to it (if you are talking about RED of Black Magic etc) but the reason why, for example, I shoot with a Panasonic is that I get incredible video output, decent stills (not as good stills as Fuji, but pretty damn fine) smaller/ lighter lenses (PanaLeica - great) and familiar handling all in one camera.
If I know I'm only going out to shoot stills I take my Fuji X-T1 or X-Pro1, for sure. I even use Fuji in the studio (sold my Canon gear a couple of years ago).
But more and more, I go out to shoot wanting the option of stills or video and only want to take one system with me. The reality is that I'm going to use what's in my hands. And increasingly that's my Panasonic. I'm not a video professional: all I want is
1) Nice clean output
2) Minimal to no moire/ aliasing
3) Manual control during shooting
4) 'Neutral' mode suitable for grading in post-production
5) 4K
Note that 4K comes last on the list. I can record audio separately so I haven't even put mic/ headphone sockets in. Getting rid of that moire is far more important than upgrading the feature set Fuji!