The problem is buying raiting, you dont solve that by making them stay 5-10 days in the guild to count their raiting, if they wanna sell their raiting they will just come 10 days earlier, it may make selling raiting harder, but it will still be a thing, with the guild history log that qeight said that staff will have in the future, they will be able to investigate possible boosting. Last day recruiting may most of the times be friends or payed ppl but often they are real recruits, ppl that will stay in the guild. If you take that from the game, that what i think will make the guild ladder less competitive. In regular ladder, you can pvp last day and climp your way up, not necessarily to the top, thats what last day rcruits offer to the guild ladder. Dont forget that that will not affect only the first guilds but those who are trying to get in top 10. But i aggree that this type of boosting is unhealthy for the game, i just dont want a fix that will just replace it with another problem.
(Sorry for replaying with my alt, didnt notice the first time that i was logged on with this acc and now there is not a point of changing xD )