People get sidetracked, the conversation drifts a little or somewhat or even a lot. Then it continues to do so. Maybe it steers back to the original point but u

People get sidetracked, the conversation drifts a little or somewhat or even a lot. Then it continues to do so. Maybe it steers back to the original point but usually only if under deliberate control. At least with tree based commenting the divergence can be collapsed at each branch. ...And I'm painting my house. We're thinking of a reddy color to match the surrounds. Then we talk about what those surrounds are, what plants, pots, the weather, when they can visit... This is actually how casual conversations work. Too strict and you lose spontaneous interesting side topics appearing. Too lax and the plot is lost completely. This is a balancing act. Reddit can go off-topic quite fast as well. Like a lot of others. This has been my experience so far on HN.