I’m not convinced of that, though it may be true for some. If it were a professional outfit doing the modelling, I’d hope they would use better techniques.
I know some are just converted from professional CAD models, but most look to me like amateurs copying something of their own just to prove to themselves they can do it.
EDIT: As for the reason for their doing it, if I were feeling cynical, I would think it must be self evident, as in Ambrose Bierce’s (The Devil’s Dictionary http://www.thedevilsdictionary.com/, ca 1911) definition: “SELF-EVIDENT, adj. Evident to one’s self and to nobody else”.