OU doesn't have nearly as many viable abusers of veil as UU does - BL constitutes a huge power creep and metagame threats like defensive Lando-T (especially with its 51% usage in OU) punish setup. Veil is also a 1-trick pony, and is extremely predictable from team preview. Things like Tapu Lele doing 90% to alotails and Spdef Celesteela just walling a lot of setup really hurts it too.I realize Hippo doesn’t like switching in but it can at least cancel veil going up and you have Scizor (BP+Defog) I just don’t see a huge difference. Thank you for explaining though.
UU still doesn't have the level of viable defoggers as OU, and lots of these defoggers are stopped directly by Alolan-Ninetales (Gliscor, Serperior, Latias, Mantine, etc) and Scizor with Defog isn't really favoring the metagame right now, especially since Magneton can just trap and kill it if it predicts its going to defog on it.
Another big part of it is that its been tested that Aurorus + Alolan Sandslash veil was at minimum borderline broken and allowing another abuser and another turn of hail just made Veil teams even better, which is why I believe the council rightly banned it.