I can only answer for me, and while I do think it's more significant a metric for me, I equally assume it probably has some influence on others as well.

C3 uses :: for namespaces, that makes it a competitor with C++ more than C. Equally Odin's syntax is more at home among python, not systems programming.

The appeal of Zig is it feels like C. To many people, this is a downside. C is very very scary to them. But for people who feel at home in C, it's not a downside.

Additionally, the selling point for both are "c replacement" where the selling point of Zig is "good systems programming language" C is only mentioned by it's users as a heuristic.

If 2 groups are trying to replace a language that people are running away from, and that's their best selling point... I'd assume they're less likely to be as successful as a different language just trying to be as good as it can be.

I've even stopped comparing Zig to C, IMO, it does a disservice to both. And I say that as someone who likes C.

Full disclosure, I need to spend a bit more time with both odin and c3 to know exactly how this compares. But the reason I keep writing Zig, and still love it, is how simple it is. Zig is aggressively insistant on simplicity at the expense of functionally or comfort. The only other high level language I know of that is as aggressive about it's design simplicity is infact C. While I assume it's an accident when C does it, it's definitely not an accident in Zig.