What the title says, basically. Again, I have no reason to assume this would be limited specifically to those with DID, but you never know, and I did notice that it was very specifically noted, so a part of me wasn't sure if this was meant to be a jam for creators with DID in particular, or if that was intended to emphasize how DID in particular is commonly misrepresented in the media. Again, assuming the latter here.
Personally, I have PTSD (and comorbid depression, anxiety, and obsessive compulsive features), and seem to suffer pretty severe dissociation, derealization, and depersonalization, to varying degrees and in varying combinations, pretty much 80% of my time awake - I mean, that percent number is just kind of a guess, really. It's a lot is the takeaway.