I think it's not her despite being in the N rarity, it's because she is in the N rarity that she was hit instead Kitkallos who is an UR like what the OCG/TCG did and what the community are advocating for.
In addition to her rarity, Merrli is especially notable for her synergy with Spright Elf and Sprind.
With her banning, Tear has lost access to 1 fusion summon and Elf/Sprind.
Yah she was seemingly banned because Konami want desperately to keep Elf and Sprind in the game. An odd choice to be frank when they could instead have hit Kelbek to 0, or just finally banned Elf or Kitkallos. Elf is gonna get banned eventually anyway when some other popular archetype finds a way to abuse it unless it gets power-crept first.