Finally, found a piece of code that doesn't look like some trainee rudiment. A breath of fresh air, thank you.

Relying on non-standard engine behavior can not guarantee you anything at all. If tomorrow V8 devs decide to introduce some optimizations that break this rule - your code is broken as well. Standards are being created with a purpose.

As for 2nd, more lines of code is not the sign of bad code - we write code for humans, not for the machines. If your code is tough for human to understand - it's a bad code.

TBH, type coercion in JS is terrible both as a concept and as an implementation. As many other things in JS. But that doesn't mean anyone should "prefer Python instead".

Fun fact - almost everyone use split/sort approach, which in fact is very slow.

This site surely lacks some kind of downvote solution function

Add one more test - set felix.weight second time and check average. This will surely show some broken solutions.