First of all you’re counting the same abilities multiple times and acting like the way his weapon functions is one of his abilities. Where’s this treatment for Orisa? Fortify? Increases damage resistance, allows Orisa to escape any ultimate, immune to CC.
Secondly, you just listed Orisa as having only 3 abilities, yet Orisa is just as powerful in the meta as Sigma. On that premise your whole argument just falls apart.