I completely agree and have always said all along that the type of light used is (of course) essential.
Filters are available for any handycam or stills camera that has the thread for it in front of the lens. There are filters for almost anything. Color filters, sparkle filters, low light filters, fluorescent filters, dual field of view filters, focus filters etc etc etc . .
The list is long and there are filters for almost any situation. They can be cheap of expensive but are mostly effective on the whole. They can address issues that normally require a lot of trial and error with lighting and other influences.
Bouncing and diffusing can be time consuming to get right when all you want to do is film or photograph. Therefor learning to use the correct filters so that one can simply pick the correct filter for a given situation once they are a little more practiced with the filters may be an even easier option for some.
Simply using lights with a4 paper taped in front of them (not touching the bulb obviously, we dont want fire . . . safety first) is also an easy option.
However, people may want a higher light level for color vibrancy which will introduce the same problem again. The filters are the solution here.
People may want to photograph or film their puppets in full sunlight. Filters are the solution here again because there is no way to strap some a4 or bakers paper to the sun.
In conclusion both answers are extremely valid depending on what the photographer is trying to achieve and what they feel comfortable using.
If simple diffusion works for you . . . use it.
If you enjoy photography and know how to or want to learn how to use the right filters . . . . use them.
For me personally, I know which filter to pick for any given situation almost immediately so I feel more comfortable using the filters in a correct lighting environment rather than trying to modify the lighting environment to achieve my goal.
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I also just want to mention that diffusion filters and diffusing the light source both achieve the same result. We are talking about achieving the same thing in two different ways. Anyone who has used diffusion filters will know this before even reading it. The real point of contention (to me) is which is easier and more versatile?
(flash goes off, lighting subject. Light reaches camera where it is DIFFUSED by a diffusion filter before entering the camera and being processed into an image by the internals)
For me, it is simply screwing a filter to the front of my camera rather than trying to modify the lighting (which may already be correct in every other aspect other than the reflections it is causing). Of course one has to provide the correct lighting but once it is done you want to be able to leave it as it is and just film / photograph rather than playing with lights the whole time.
Peace