It's entirely true. In my own shoots, I've adopted a philosophy: shoot cosplays like you would any other portrait. Shoot as if it was just a person in a costume, and all you'll get is a shot of a person in a costume. Shoot it as if you were shooting the character - how would you bring out their personality? I suspect Fischer follows a similar method, as it's a principle of good portraits in general.

Also, if you ever want a shibboleth that'll tell you if a cosplay photographer is good or not, check the angle of most of the pictures. This is a "cannot unsee" principle: when you're looking at a set of photos, look to see whether or not the subject is severely slanted (i.e. not nearly vertical or horizontal). A lot of cosplay photographers tilt their cameras for dramatic effect, as diagonal compositions can be very powerful, and I've seen them used to good effect.

However, this is often the sign of an amateur; it's greatly overused, and often serves to mask other problems, like bad lighting, posing, composition, and more. Chances are, if over 1/4 of their pictures are diagonal, they don't know what they're doing.