And his age of course.

One of my all time greats McArthur, a fantastic player for our club, love the man.

McArthur for me was always that player who was consistently good across all aspects of the game, on a regular basis, and could chip in the odd goal/great moment.

Kouyate I also think has been one of our best buys of modern times, love him equally and again a great asset for us IMHO.

Do consider them slightly different players: Kouyate being a tall, more defensive holding midfielder, JMac being an all singing all dancing CM who can do a bit of everything.

You can keep your Xavi/Iniestas of yesteryear! I'd have prime JM & CK anyday! JM past his prime now, Kouyate a younger man and position/role less physically demanding so probably the more useful for us a/would be most sorely missed at this moment in time.

Kinda hard to believe that at this stage of the season our goal difference is +17 over last year but we have three fewer points

Kouyate doesn’t get the credit he deserves. He has been a fantastic buy for us, played CB for a season to help the team out and did a great job. Now back in his favoured position in midfield and putting in great performances, but he generally goes unnoticed.
I would suggest, we would miss him more than McArthur.