It’s a weird one this because it is SO easy to trace with digital art it does feel a bit like cheating. But when you consider other mediums, and how it’s called ‘transferring’ the lines/composition, that often isn’t regarded as cheating.
For example - doing portraits or drawing/painting of a house or specific item from a provided photo. You’d want the proportions to be as close as possible and so using a backlight, or rubbing soft pastel on the back and going over the lines would probably be seen as quite acceptable to get the outlines, and then fill it in by eye with your medium.
There’s even YouTube videos on how best to transfer your lines to the paper or canvas. And I don’t think many people would have an issue and object that it was ‘traced’. Maybe because it’s still kinda fiddly to transfer the outlines using traditional methods.
But being able to put your reference photo directly under a new layer, and even zooming in to be super precise, is sometimes viewed as cheating. Like I said, maybe because it’s just so easy to do.
I’ll hold my hands up and say I sometimes trace outlines of things. You can spend hours trial and error trying to get a specific proportion just so, or you can utilize the convenience of digital art! You still need to use your skills to fill in the lines how you want to.
If we go down that route then you can argue that all of digital art is cheating - shading with the multiply layer, adding blur, adjusting colour values, using stamps of leaves and grass etc.
As Sooz says, as long as you’re not tracing someone else’s art work and claiming it as your own, I see no issues at all with the convenience of tracing.