Not only are you trying to be pedantic, but you also don't even seem to understand the rule you're trying to be pedantic about.
That method does accept two parameters, since two is in the range of 0..N. The opposite of accept is reject, and if that function rejected
two parameters, the tests would not pass.

Also, why are you criticizing people for improving the function by not limiting the amount of names a person can have? At least hundreds of millions of people in the world have more than two names.

This is smart!

This is pedantic but the description does say:

Create a function ... that accepts two parameters

Although the test cases doesn't test for the amount of parameters, this solution would technically be incorrect as it accepts 0 to N parameters.

Excellent Solution!

What does "more effective" mean to you?

See my solution, it's more effective.

Great explanation, thanks!

Hi!!! why was the "|| []" included?

spoiler flag...

Could somebody explain code in return ? I'm a newbie and i'm trying to understand this code ...

You don't even need to transform it to a set, because keys are unique within a dictionary, so duplicates are discarded.