An interesting take on reduce and Object.assign

In this article Why using object spread with reduce probably a bad idea I saw this strange line of code:

someArray.reduce(Object.assign, {})

I thought Object.assign was meant for merging objects. Why the reduce? What is going on here??

If I want to test some JavaScript I run node in a terminal to create a playfield:

[1, 2, 3].reduce(Object.assign, {})

// output:
{ '0': 1, '1': 2, '2': 3 }

Ah, good to know, might be handy sometime!