They almost universally aren't, that's BS.
Can you explain? because I think DSLRs are great for the job.
DSLR's vs dedicated videos cameras: (may not be current, very camera dependent, but in general)
- Most cannot maintain focus while zooming
- Most cannot do variable speed accelerated power zooming
- Many have silly stuff like noise from the zoom motors getting into the audio.
- Many lack a fully articulated screen (it's
Youtube, you need to be in front of the camera sometimes and see the screen)
- Most if not all lack proper dB audio signal level meters, essential in my opinion.
- Most lack proper audio features like proper manual ranging audio without horrible compression. External mic input is no good if it has fixed dynamic compression for example.
- Most have crap inbuilt mics (yes good video camera's over a few hundred dollar generally have good quality mics build in if you are close enough to them (e.g. behind camera))
- Most lack focus peaking
- Most lack zebra stripes for exposure
- Most lack dual SD cards for fexibility and backup.
- Many lack dedicated buttons for often used stuff like video exposure etc.
- And because they are designed for photos and not manual control video, they are just more fiddly to use to shoot proper manual video.
And there are probably more, but it's almost 1am and I'm tired...