I know of an example first hand where syntax only mattered: OCaml vs ReasonML. ReasonML is merely a syntactic change from OCaml as it's simply OCaml underneath, but people, especially coming from web languages like Javascript, liked ReasonML more than OCaml and were more willing to use it.

Another example, Gleam (an Erlang BEAM based language like Elixir) [0]:

> Shot in the wind, but is there a plan for different syntax? For those who've become comfortable in different fp camps, I can't really see myself picking up curly brackets and C-style code again. I really like the idea(s) of this project, but it's the thought of staring at that kind of code that's just a bit too much. I'd rather do something like [Nim,Scala,Clojure,F#]->JS if I needed to have that.

> > Unlikely I'm afraid. We used to have an ML style syntax but once we switched to a more mainstream syntax we had a big surge in popularity and interest.

> > I am very fond of the ML syntax, but I think it is the semantics and type system that really matter, so I am very happy to sacrifice syntax in order to make Gleam more widely accessible.

[0] https://news.ycombinator.com/item?id=27063049