If things get busy, it’s easy for 2 days to go by before I can reply. 2 weeks would be better to account for busy schedules and vacations, in my opinion.
Someone gave a very helpful solution to my question, and by the time I was able to try it and respond, the topic had been locked, and I had no way to thank them. 
You have to accept a comment as a solution before the 2 days kick in and the topic is locked. Perhaps you can delay that after testing the solution, thank the person, mark their comment as the solution, then the topic is closed.
My only issue with the short closing window is that, sometimes I have follow-up comments on the same topic, but then I have to open a new topic.
The topic was auto closed before I could look into their solution at all, so nothing was marked as the solution. I marked their reply as the solution after it was auto closed.
@Arif’s description is correct. Not sure what happened in your case. Create a new topic if it happens again.
It was How to organize static and asset files from the same npm package? - #2 by jmooring.
It didn’t seem appropriate to create a new thread just for a thank-you.
But since you’re here @jmooring, thank you!
At the bottom of the thread, it says:
This topic was automatically closed 2 days after the last reply. New replies are no longer allowed.
Create a new topic if it happens again.