As far as I can tell looking through core files there is no deprecated note on this constant, the article has an odd edit by user name not seen before who also does not figure in revision history, checking all the user revision history existing shows no one having added that so must be this mystery user & their last article edit. I’ve removed the deprecated addition for now.
@henrywright if you have a minute might be worth jumping into irc and asking if anyone else can confirm that root profiles are safe, as for the edit I’m very perplexed by it, had thought I had done it in error 🙂 I worry about curating codex now though 🙂
Root profiles are not deprecated, though we have some planned obsolescence for almost all of our global constants, moving them into functions with filters and/or options.
Our rewrite rules improvements for BuddyPress 2.0 will ideally enable any component to exist at a root level. At the time that code was written, it solved an immediate problem for us, but going forward this feature should not be exclusive to profiles.