Unix shell scripts are one of the few holdouts.

I don't know if this applies to other shells, but bash will not only execute your script line-by-line, it will also read it line-by-line. Which means that you can modify the behavior of a running script by editing lines that have not yet been executed*. It's absolutely bonkers, and I'm sure that it has caused more than one system failure, during upgrades.

* For example, if you run the following script

echo "hello"
sleep 5
echo "goodbye"

and then edit the third line before the 5 second sleep has elapsed, then the modified line will be executed.

It is normal usage. Though personally I'd probably make another "main" function, to avoid declaring a bunch of global variables

But if those beginners want to stop being beginners, then they must learn the basics of the language. It makes no more sense to demand that everyone who programs in Python caters to beginners, than it makes to demand that everyone writing in English write at a 3rd grade reading level for the sake of English language learners

Containers being "truthy" is quite basic Python and you will find this idiom used in nearly every Python code base in my experience