When that happens it just gets confusing, because it’s hard for people know which thread to comment in, if the comment they want to make is somewhere in the overlap. And then whichever one they choose to comment in, people who only see the other thread won’t see that comment. Then sometimes, anticipating this, people will copy and paste their comment in both threads (which happened in this case). But then each one gets different replies.

So each thread ends up being incomplete and duplicated all at once, and it all becomes a big confusing mess.

The fact that these two articles were by the same author, had the same title, were published just a week apart and could easily have been published as one, longer article, says to me that merging the threads was the right thing to do.

The other option would have been to bury the second thread and consider another thread about that second article a few months later, but that didn’t seem like the best option, given how much the two articles are so related and continuous.

Edit: Just thought I'd add that a major factor in deciding to merge the threads was this opening to the second part by the author:

The first article in this series provided an overview of Home Assistant, its community, and its capabilities. It was deliberately short on descriptions of interesting things that can be done with Home Assistant, though — the reasons why one might actually want to use this program. In this closing article, we'll look at how Home Assistant was used to solve some real problems.

To me it makes all the difference that the first part is introductory/high-level whilst the second part goes deeper into usage-scenarios. We'd treat it differently if each part went deeply into different aspects on the project.