In the defense of players bringing their alts:
When there are a limited amount of people in a certain time zone (or people who don't like playing the game for the social aspect) its easier for them to just lover themselves with an alt for the 10% exp boost when grinding.
Even if their alt isn't in a party being power-leveled and just sitting at the tele for them to get their exp bonus (Mind you, +10% exp is actually really helpful because the GM's and devs still refuse to give decent exp from regular non-dungeon mobs), it shouldn't be seen as bannable offense.
They're not harming anyone and certainly aren't inhibiting anyone from playing/enjoying the game.
I also agree with dx0520:
My only concern is that the burden of enforcement is placed upon the players in this game, moreso than any other game that I know of, which develops into a culture and attitudes of players that are basically at each other's throats.
There are going to be so many people on their high horse just spending their day searching for people who are under 71 in that zone, and whispering them saying "You're under 71, leave or I'll report you" or just simply "SS'd and reported". I know for a fact that GSSnow whispered someone with a 67 alt there who wasn't in a party and just grinding with the exp buff.
Also might I add that you can get level 71 quests at level 69, so I think that the new map should be reconsidered to include 66+ instead of only 71+, if anything.
However, I do not see the issue is so big that it deserves more attention than people losing all their costume, 80 yellow gear, and nerfing +15 gear that was fine the way it was. (Woo yay for long opinions)