Only because that's the topic.
If you think Calvinist salvation by election is the same as all the others, you haven't spent much time on these threads... :)
The are a multitude of other heresies concerning who Christ is besides that of the Oneness Pentecostals - modalism. There are modern day sola scriptura adherents of Arianism, Nestorianism, Gnosticism and so on.
Then see above.