We weren’t required to offer both tiers in the beginning (which I didn’t), but later the Agreement changed and they sent us an email informing that both tiers became mandatory and we wouldn’t be able to make updates to products that didn’t have the tiers. So I waited until I needed to make product updates (UE 5.5 came out) and then I included the tiers.
If you see products without the tiers I suppose it’s because they were never updated after the change in the Agreement. For instance, they can’t include compatibility with UE 5.5.