Their QA team consists of hundreds of people, so testing guildhests should be quick and easy relative to everything else.
People still do guildhests because meeting sprouts in them is extremely common. A lot of the time it is the very first multiplayer dungeon of any form that a sprout does.
Doing levequests is actually something you may find new players doing, even if nobody would recommend it. They are used as relic weapon steps and to spawn hunts so these would have to be adjusted.
