It happened to me a couple of times while writing a post, my computer restarted due to a power outage. After rebooting, the text I entered was still there. No special cache settings. (Chrome browser)
Also, the preview button saves the currently written post into a draft and is available there for 7 days. It seems to me that this is quite enough from the "outdated" version of the software.
It happened to me sometimes as well and fortunately the posts that I were writing were saved as drafts and when I repowered my system I was able to complete the posts from the state I left them when power was off. I'm thinking about shifting to a laptop as that one will be much helpful for me because I can run a laptop on low power UPS and there won't be any power outage issues. But, surely that feature of the forum saves us sometimes.
It's first time I get to know that preview button saves the written post into a draft and that draft is available for a whole week. I believe that such feature are pretty helpful mostly for those users who give time to write the posts and sometimes the posts get longer due to information that's added into the posts.