Might I bring up the topic of Master Studies?
Now...Master studies aren't exactly tracing in the sense that we use it now. It's more involved than simply tracing over a piece of work. You actually have to do your best to replicate what the artist did with the original piece. Moreover, the idea behind these master studies is to work on topics like shading, lighting, structure, etc. You break down the OG piece to its foundation and then try to rebuild the same piece again.
Master Studies are examples of replicating original works; maybe not tracing, but it felt relevant to the example of this artist drawing that model. They're more of a higher example of when people do re-draws of their favorite screenshot from an anime or a show.
Of course, the difference with Master studies is that there is more credit given to the original artist, and you can kinda tell the replicate artist didn't do the OG piece because most of the time, they're out and about saying "yeah, I did a Master Study of this piece by -insert artist-"
I do feel that if there was no obvious credit given, it should've happened, and I do feel that if you're making money from traces or replicates, you ought to be giving royalties to the OG artist. But, if it's just for learning or just showing fanart, like in the case of Master Studies, it's all good. Just show credit (even if it's as simple as "oh! here's a picture I drew of these people I saw downtown!").