For me, text is always helpful. Sometimes I cannot understand what the arrows
mean especially when there is more than one arrow in a step (and this is
speaking as a Non-Beginner). The best part about text is that if I understand
the arrows, I just ignore the text. The textual description is just an extra
way of explaining what to do. People who need it can use it. People who don't
need it can ignore it.
This means, on a website where you have infinite space, I think you should
always include text if you can. On a published book, adding text may not be
realistic due to space constraints.
Sometimes I write, "Fold the paper in half from left to right to form a
rectangle. Unfold." You would think that a fold-unfold arrow would explain it
all. But not so, I have people saying that they like the text because when
they are teaching other people to fold origami, they say exactly what I write.
This allows them to read what I wrote instead of saying things like, "Fold the
paper like this. Ok, so now, do this."