I didn't know we still had that! That is left-over from long ago. 😮
If you click and drag, it will make a two-point spline.
Back in the dark ages, "A" would get you just that two-point spline behavior and you had to SHIFT-A ("lock mode") to get the continuing spline-making that "A" gets you today.
I think you can ignore "lock mode" today.