You are just arguing that a simple language is good for beginners, and I agree with that.
We want a beginner language which has easy (and consistent) syntax, no requirement to specify datatypes (implicit), and can be interpreted (no compiling required).
In its most basic use, namely just writing procedural code with basic built-in data structures, Python is pretty ok. But it has some warts and gotchas, not the least of which is mutable default parameters in functions.
Now maybe the ultimate beginner doesn't use defaults for parameters, so it's not a problem (yet) for them. Same goes for the OO features. While the beginner may not write OO Python, using modules written by other people probably will require them to step into the Python version of OO. Now it gets messier.
Ruby is superior in the simple beginner case and the complex (OOP) case. It is superior and more consistent for functional cases as well, despite it not being designed as a functional language (it still has mutability risks all over the place as does Python, except for that default parameter razorblade).
The only beginner-unfriendly thing I can think of for Ruby is the optional parenthesis on function calls. I still think optional parens is a bad design choice, and I encourage people to always use them. It's usually a style choice (but not always, because sometimes it matters for how code is parsed), and I think it's better to know as a reader that foo.bar() is a function being called. foo.bar is unclear.
One small but significant feature Ruby provides is the ability to write more expressive function names with ? and !. A common pattern is to use foo? to indicate that the function will return a boolean. The alternative, without ?, is is_foo(). Likewise, ! usually (at least for standard libraries) indicates mutation.
Back to the point though, Python used simply in isolation is not terrible for a beginner. But inevitably outside modules will get used, and the misfeatures of Python will appear more frequently. And then a further eventuality is that this new programmer will now be a "python programmer", choosing Python for future bigger work because that's what they know. Why not start with a language that is also beginner friendly but also better for large, long-lived projects?