I've been contemplating this for awhile and I have absolutely nothing good to say about joining guilds early in the game.
1) Unwanted guild priorities become your priorities/responsibilities/vendettas, weather you want them or not.
2) Lower level players will beg the higher level players for resources or other one sided deals
3) Early guilds are usually filled with whatever rabble the leader can dig out of the server regardless of skill or intellect
3.1) This rabble usually spams guild chat rooms with complete garbage and makes guild chat useless as a medium of communication....
4) Any help a guild offers is readily available without the need for all of the above simply by using the global/help chat sections.
5) As in the case of Demacia/Garen (apparently they were one and the same person from what I heard) and his guild TC (The Creators), he required sketchy donations from all of the people joining the guild, I assume to help build the guild hall, then went on to get banned and now the entire guild is out a good chunk of res for nothing.