My $0.02:
We are users cataloging what we own or once owned, based on the honor system.
The Artist profiles are a catalog of what that Artist has used, but not necessarily owned, based on reputable photographic or print evidence.
Two different contexts. Apples and oranges.
At times, it does seem weird to me to attribute something the artist used that belonged to a studio or to another artist, but 14 year old me would be coming here to find out what guitars and FX Andy Summers used on the early Police albums, or what Billy Corgan used on Gish... and I wouldn't really care if they owned that gear, borrowed it, stole it, or found it in the studio's gear locker... I'd just want info on what was making those sounds I'm hearing from all these BMG Music Club CDs.
Also, there is no practical way to verify what an artist owns vs. borrowed vs. used just because the Engineer put it in front of them. It's a level of detail that would break the fragile social contracts and unspoken agreements that keep this site moving forward.
So, yeah, if they verifiably used it live or on a recording, it's fair game as far as I'm concerned. Establishing legal ownership would be a weird and potentially counter-productive standard to impose.
Also: As users, we have the ability to create a separate category on our board for gear we've used, but do not own... especially when it comes to things like big consoles, expensive vintage mics, and speakers that cost more than a good used car. If anyone here had experience with such studio staples, and wanted to add it to a clearly marked section of their board so they could comment on their personal experience with such gear, I think that would be awesome.
...but again, just my personal take. Others will surely differ.