I am a first year beekeeper, so my opinion may not be worth a lump of coal. But, I started in April with one hive, after having caught a wild swarm. I had planned on ordering one when I got a package of bees lined up. So, I ended up with a swarm instead, and when I tried to order an excluder, everyone was out of stock.
So, my bees filled their hive body plus two supers, which we extracted, and then refilled a super. The queen never laid in the supers at all. She seems to stay down where she is "supposed" to, and lets the workers keep filling the top with honey.
As of now, my opinion is that for me, they aren't needed. I reserve the right to change my opinion at a later date though LOL.