However, despite the fact that I used to use LaTeX very much, I always copy-pasted from a template. It is even worse with beamer presentations and TikZ pictures where I would copy-paste from a previous presentation or picture rather than a template.
For TikZ I am pretty sure that the tool is inherently complex and I just haven't spent enough time to learn it properly.
For LaTeX I have certainly spent enough time on learning it so I wonder whether it might be something different.
In my opinion it could very well be a matter of “(in)sane defaults”. Good tools should come with good defaults. However, LaTeX is not a good tool wrt. this metric, because basically all my documents start something like
~~~ \documentclass[paper=a4, DIV9, 12pt, abstracton, headings=normal, captions=tableheading]{scrartcl} \usepackage[T1]{fontenc} \usepackage[utf8]{inputenc} \usepackage[english,german,ngerman]{babel} \usepackage[english,german]{fancyref} % ... \usepackage{microtype} \usepackage{hyperref} ~~~
Most of this is to get some basic non-ASCII support that is needed for my native tongue or enable some sane defaults (A4 paper, microtype...) which in a modern tool like e.g. pandoc/markdown may not be needed...
Hence the purpose of copy-pasing the stuff around is often to get good defaults which a better tool might give you right out of the box (then without copy/paste).
For LaTeX I also copy-paste a whole lot from older files, but I don't feel bad because (a) I wrote these files before, (b) I know exactly what each line is doing, (c) I understand why each line is needed in the new doc.
I wrote a relatively large amount of TikZ code earlier in my life (basically used it as a substitute for Illustrator) and for this library in particular, I think it just has so much syntax to remember that I cannot keep it all in my brain for ever. So I gladly copy from my old TikZ code.