The odds of another tourist stealing your camera when you ask them to take a picture is pretty much 0%.
The odds of a someone (especially a poor local) who asks YOU if you would them to take a picture of you
stealing your camerais pretty much 100%.
My country (Israel) is full of tourists, and when I see them taking turns photographing each other I offer to photograph the group. I've never stolen a camera, and others do as I do without stealling cameras. I suppose that your advice might be culture-dependent.
This is the same advice I give my kids. If you get lost, don't
wait for someone to approach you, instead walk up to the first person you see and ask for help. Most people
are normal law abiding citizens, if you play the odds and pick someone randomly then your chances of getting
a criminal are very small. If instead you let them approach you then they are picking you which makes the
odds of them being a criminal considerably higher.
That is good advice for kids, and I will in fact start giving it.