English has Rules, Just Like Japanese!

[Iscah]

When I don't know someone's gender I say IT or THING. As in, "what is it!?" Or, "look at that thing!"

And how would that work with the examples given in the Wikipedia article I linked earlier?

"Somebody left their umbrella in the office. Would they please collect it?"
"The patient should be told at the outset how much they will be required to pay."
"But a journalist should not be forced to reveal their sources."

Could you write those sentences with "it"? Would that seem appropriate? Would it be better English?

"Somebody left its umbrella in the office. Would it please collect it?"
"The patient should be told at the outset how much it will be required to pay."
"But a journalist should not be forced to reveal its sources."

It might be grammatically correct, but it's not the normal word you use in that situation.

There's nothing new or remarkable about using "they". You probably don't even notice it in most contexts.