Well seeing as you are arguing both are pens, but only one was given, why would I be singled out as 'throwing stones at clouds' ?
Andfl no they haven't always followed that rule, it's a relatively recent addittion to the rules, but the defenition of 'unnatural' is being used either for the sake of argument or to excuse inconsistent/bad/bent refereeing. There was absolutely nothing whatsoever 'unnatural' about the arm position of either player in either similar penatly incident. Your arms do all kinds of shit, naturally, when you play football.
The correct defenition is, of course, when a player deliberately sticks his arm out to block a cross or shot, or, as correctly shown when Umtiti recently handled the ball above his head deliberately, rather than it happening due to natural balance or momentum . It is the ref/v.a.r. job to not be robotic in it's interpreteation & rather, use the law in the spirit it is intended, which is purely to stop intentional foul play, not give pens for accidents, because almost every incident involves an arm in an, 'unnatural' position, in a huge variety of circumstances, and always has done. It's not a new movement.
Unnatural position ALERT!!!
VVVVVVVVVVVVVVVVVVVV
That's where v.a.r. might have actually been some fucking use, instead of manufacturing incidents which aren't there.