+4
Yeah, I think it's just easy to assume that Suspiria is giallo simply because it's the most well-known film made by a prolific giallo director like Argento during the genre's peak, but the supernatural elements push it away from the mundane murder mysteries that constitute typical giallo movies.
Anyway, a quick glance at IMDb has a bunch of the major giallo titles be tagged as horror so it seems they are all eligible by the established criteria.