I've been using the scale tool with discrete scaling along edge loops to align the vertices along the same axis. Initially I was just using this to straighten out my geometry, but I also realised that by doing this and aligning the scale axis to a relevant face (or whatever custom axis orientation) I can align different edges to one another. I know, I know, pretty basic, but I've only been modeling for a couple of days, so this was quite handy for me to discover.

My actual question is: why does discrete scaling have this effect? I was googling how to straighten out / align my vertices which is how I came across the initial solution, but I wouldn't have figured it out myself. I can say that pretty safely because now that I know what to do, I still don't understand why it's happening.

Specifically, I don't understand why vertices will lock at the same point if you scale discretely along a given axis instead of just continuing to be scaled onwards in steps, which is what I would have guessed would happen. Is the step size important to what I'm doing? I wouldn't have assumed it was, and changing it doesn't seem to make any significant differences the behaviour.

If someone can explain in layman's terms to me what is happening I would hugely appreciate it. If this was an align tool that was specifically intended to do this exact thing then I wouldn't question it, but because it's interesting behaviour in the scale tool I'm trying to find out a bit more.