From #15330 (comment)

I've come across two use-cases where this scaling behavior is undesirable:

• I'm plotting a line with a single special point (eg, a ray, and I'm ok with the backwards portion of the line). If I plot (origin, origin + direction), then my axis bounds scale to meet origin + direction, even though that point is arbitrary. I can work around that with a hack like (origin, origin + eps*direction), but it forces me to trade off axis scaling against precision.

• I'm plotting a true infinite line, with no special points. Perhaps ideally I'd get axis scaling that shows the "nearest" part of the line, but I'd be ok with just passing autoscale=False to axline to have it skip this step.

Originally posted by @eric-wieser in #15330