Add-to-list or setq append...

[Andrea Crotti]

Just a curiosity, I was wondering why in so many README and doc they
suggest to add elements to lists with something like:

--8<---------------cut here---------------start------------->8---
(setq list (append list element))
--8<---------------cut here---------------end--------------->8---

instead of doing simply
--8<---------------cut here---------------start------------->8---
(add-to-list list-va element)
--8<---------------cut here---------------end--------------->8---

Is there any good reason or is just historical heritage?
I think add-to-list is even more smart adding only if not there already,
then what's the point in using that ugly form?