More guarantees as in asserting on exact data shape which also includes some typing guarantees like "function argument 1 is always gonna be this struct" (basically a map with keys guaranteed to be present).
In Ruby you get nothing like that, all your function arguments are just variable names. This increases testing friction a lot. I've been all over the spectrum: from PHP and Ruby through Elixir (combining best of static and dynamic types IMO, though still flawed) to Golang and finally to Rust which is super strict. To me Elixir and Golang are close to perfect. Rust takes it too far and development velocity can suffer a lot until you become an expert (which can take quite a while).
Plug and play is nice but my opinion remains that it's oversold. Quickly whipping out prototypes is not the only virtue of a programming language (though technically that's a feature of Rails, Ruby's killer app, and not of Ruby itself).
The problem is that is only so helpful anyway because you have to send the data to the front end and then translate it back, and in my experience that is where most of the issue is. If you are building a front end facing site you are constantly going to be fighting with that.
Yep, agreed, and I am saying that as a guy who still prefers server-side rendering.
Stuff like Elixir's LiveView and its imitators (like PHPx and I think C#'s Blazor?) are where things get better but since I am not interested in frontend, I leave that work to other people.
