1. They didn't have a big, well-known, company name with good enough reputation to attract contributors.
2. They didn't have brackets.
Success was because traction, traction was because appeal, and appeal was mostly because those two things. Nothing else was new AFAIK.
A lot of them simply assumed that some amount of "overhead," vaguely described, was acceptable to the target audience. Either tracing GC or reference counting. "but we're kinda close to C performance" was a thing that was said, but wasn't really actually true. Or rather, it was true in a different sense: as computers got faster, more application domains could deal with some overhead, and so the true domain of "low level programming languages" shrunk. And so finally, Rust came along, being able to tackle the true "last mile" for memory unsafety.
Rust even almost missed the boat on this up until as late as one year before Rust 1.0! We would have gotten closer than most if RFC 230 hadn't landed, but in retrospect this decision was absolutely pivotal for Rust to rise to the degree that it has.
Their problems was a mix of not being hieroglyph languages (too much text to type!), being much strongly typed (straitjacket programming with a famous rant post, wrongly), commercial offerings being expensive (more so against free in the box alternative), and not comming with an OS to make their use unavoidable.
Note that for all the hype, Zig is basically Modula-2 features with C syntax, to certain extent.
Early MacOS did use Pascal, though IIRC not Object Pascal.
This is a bit of a nostalgia trip for me as I owned a copy of this book way back in the 90's
https://developer.apple.com/library/archive/documentation/ma...
The getting traction part is the relevance part.