There have been suggestions for both spoilers and collapsable quotes and I think they'd be both useful additions.
I am not very aware of this, although I understand that it will be more difficult than just
“add”. But the implementation of this tag can certainly be done using PHP tools. Even it would be possible to close eyes if the text of the heading could not be formatted in accordance with the preferences of the user.
Although it would not hurt to add the ability to replace the text to the left of
[spoiler] (editing or inserting a small graphic / symbol, which would also open the spoiler). Whatever it is, the information should be hidden before clicking and open when pressed again.
I think this goes with any feature/changes for now. Even the small features/changes that could potentially improve the forum in general isn't being added(as far as I know). Looks like all focus is on the EpochTalk forum. Hope it doesn't take more years for us to migrate to that software though.