In the first few of years of TiddlyWiki (mid/late '00s), the way it worked was that you just had a local copy of your tiddlywiki.html. You just opened it in a browser, and did your editing. Then you could just click the save button inside the page. And the page was saved to disk. This worked on every desktop browser.

Obviously, generically letting webpages, even local ones, have this sort of access to disk had lots of security implications. So, eventually all browsers removed this functionality. Now, you need all these extensions or tools to save the file.