Some fanatical types will want to read every post on a forum. I certainly do.
Currently the way to do this is to go in User Preferences and manually enter every category into the “Tracked” box. Besides being a real pain, it’s hard to teach users to do this. And, if a new category is added, it has to be manually added to this list as well.
Can we have a “Track all” option, that will cover all current and future categories automatically?
OK, I hate it when this happens… I think I found the answer to my own question (AFTER I posted… )
https://meta.discourse.org/t/marking-all-new-topics-as-new/27451
For anyone else wondering, You need to:
Set Consider topics new when to “I haven’t viewed them yet” (this is the default)
Set Automatically track topics I enter to “immediately”
Do you want notifications for every category, for every post created?
Or did you want a simple visual cue in the topic listings, as was my problem in the post linked above? That you never touched the topic as of yet in that moment of time?
Just the visual cue, “something new to read!” Not a notification, that would be annoying.
When I imported an old forum earlier this year, all the old topics were un-tracked, and I had some issues tracking them when new replies to old topics showed up. That’s why I ended up tracking all categories.
On a “new” forum without a large backlog of old posts, this is unnecessary.
Aye, by setting every single future topic “to be tracked”, that equals a lot of bells and whistles going off you would not wish upon your users. 
My fix came eventually; not directly.
Since I started that topic you linked above, the UI now colors the titles of topics not yet entered in the topic listings.
EDIT – In further hyperfocused thought, “read previously” is analogous to “topic that was created pre-registration”. Either way, a black title sans 
tells me there’s content to plunder I have not yet thoroughly plundered. Context and whatever my inhibited organic memory managed to save in browsing will let me know if this is “read previously; has new posts not seen yet” or “this topic predates me (*grunt*) via registration date, but it got some goods you have yet to predate.” I consider my initial gripe in the aforementioned topic resolved. And much obliged for that–Discourse Dev Team and Volunteers–considering I made this edit in pure elation over these now-default visual, immediate prompts to denote distances in time for topics and the replies within; something that eluded me prior from my lack of natural cognitive awareness for time itself.)