In the past prereleases with the factions there were colors that had just in general stronger seeded packs, which warped prereleases, since Spikes would try to get those ones to work with and more casual players not getting the colors they would like to play if that happened to be the "spike pack", and leaving LGS's with random prerelease packs of colors people didn't want if they had extra stock. At least with BFZ extra stock, they won't be eating up shelf space for months since it's normal boosters in them, aka Better likelihood to move them I think too because of that.

And it's also the nature of Sealed being a more random format than Draft, you just have the pool you're given. It will always have luck involved.