Well like for instance here is a good example within this old random post where the person tried.
This person was trying to put a lot of a particular reference info into a post, but at the same time not have the post be so long, but have all the the info he wanted available in full if one clicked on the spoiler tag - then it would open up in full; otherwise it would be collapsed hidden and only taking up one line.
I think it's a good idea too, and a few times over the years I wanted to use it's function but it was not available here in this forum like it is other forums.
No big deal, but just a good thought and wanted to express...