Photography is a very useful tool, we can’t hope to capture the detail the a photograph can.
As I have said often, photos are very useful when they are the only way to get information, they provide unlimited access to many things that would be unaccessable without them, exotic animals, foreign lands and yes nudes. Of course we all have one nude model available if we own a mirror. The problem is not the use of photography but how it is used.
The camera sees far to much and captures an overabundance of detail.
Every photo is full of unpleasant detail and every photo has the possibilities of something charming. We must study hard to decide what shall stay and what shall not. If the values and planes go in well, if the softness and sharpness are taken care of, such irrelevant detail well not be missed. We can beat the camera, because the camera cannot choose nor subordinate, thank Heaven.
Degas, Eakins and many others used photos as reference. Of course they were master draughtsmen and did not learn to draw by copying photos. They used photos to help with composition and value and other design issues. Again a matter of understanding the way to use them.
Lighting becomes a hugh issue.
Ahead of everything else choose or take photos with very simple lighting, one basic light whenever possible for the best interpretation of form.
Nature takes care of that, outdoors. We mess things up when we take over inside.
Photography is a quick convenient way to record something to be painted later. It can also serve as a supplement to drawing/painting from life, as a reference for touch-up work, or as a record of detail for corrections. Photos are useful too for gathering ideas for drawings/paintings to be done from life, or as an informational tool used in the same way as a quick sketch.
Photos are often the only way we can have access to certain subjects as Rebecca has pointed out. Even though it is not an ideal access it is better than no access at all.
It allows us to capture things that are impossible to paint from life— thing that move too fast or exist as very brief effects. (like snowflakes) Often we would like to draw or paint certain things, but there is no vantage point from which to paint, or other circumstances make it impossible to set up our painting equipment. A camera brings those otherwise inaccessible subjects within our reach. Artists with special needs, the physically handicapped, the confined, could not experience certain kinds of painting at all without photography.
On the other hand…
Cameras are recording devices, not experiencing devices. A photo is the product of a machine that simply makes and impassive visual record of whatever it is pointed at.
Unlike us, it does not think or feel. They are technically smart, but life-dumb instruments.
They have no sensitivity.
Cameras do not give a true technical picture of what we see. They only record what they are designed to record, and that is both qualitatively and quantitatively different than what we humans see. Except for capturing detail, at which they are better than us, they are remarkably limited. The sensitivity of photographic film is trigling compared to our human sensitivity; its color and value latitude is only a tiny fraction of what our eye-mind combo sees.
Once again this the 21st century and we have great tools at our disposal we only need remember that they are mechanical devices and have no brain.
I of course have a great camera and dozens of lens and have drawn often using photo reference. It should be the last choice and not the first when ever possible.