I’ts been like that since I can remember. Probably there was some issue keeping some of the information correctly up-to-date and was left aside. The top set of stats seem to be working, although you need to consider the time period behind (i.e. Average registrations per day seems to ponder multiple years, and is not a moving 1 year average for example).

If you’re into stats, there’s a bunch more (non-official) listed here:List of Bitcointalk stats. Most of them are one-off stats, and a few are updated periodically. Not all are included there, as some recent ones are probably missing.

Out of the items listed in the Forum History section, some of the above stats have continued to register a few of those values. For example:

* Registrations:
  Statistics of user registrations on Bitcointalk 2017-2019
  Assumed monthly statistics on registered accounts of bitcointalk.org (2009-2019)

* Net (Created – Deleted - Moved) Post count (see https://public.tableau.com/shared/5G8SFTFN7?:display_count=yes&:origin=viz_share_link