I think multi is just the added responsibility. It's another way to distinguish pilots. I compare it to turbine PIC when applying to a major. You can have 10,000 hours of 121 SIC time but not be competitive when compared to someone with less time but 1000 PIC. Is PIC important? Of course. But I don't think it makes someone without PIC unqualified. Same with multi time. It's harder to get than single time, so it stands out more. Just my take...