A lot of people have versioning problems in all languages. You said "Meanwhile, all I had to do to update old Python Lambdas was just update the runtime itself. ". You know that isn't always true in Python that you just update the runtime and nothing goes wrong.
The reality is that JavaScript has become an ungovernable language; Python's dependency problems are nowhere near the current horror of JavaScript, where people keep using all these tools made by startups creating problems bigger than the problems such tools were supposed to solve, and those new problems are solved by a wave of new tools from more -or even the same- startups, and this in an endless loop, because people adopt it again.
At work I deal with javascript dependencies, ruby dependencies, php, and others. Dealing with keeping versions up to date sucks in every language I've used.
