guild experience isn't normalized by level?

Is there a reason why guild experience isn't normalized by level?

I do the fishing daily on my level 85 main, and I get 17k guild XP. If I do the same quest on a low level alt-- same quest, same or more time spent, since most of my alts can't fly yet-- and I get less than 100 guild XP. I could quest all day on my alts, and not get any meaningful amount of rep or XP until I got them to level 80 or so. As a result, new players and alts are unable to contribute to guild XP, or gain much world of Warcraft po guild reputation, until they're very close to the endgame.

I know right now there's a direct relationship between XP gained and guild XP and rep gained. However, XP tends to scale exponentially, which means that the only characters who matter, as far as leveling the guild is concerned, are usually around level 80 and higher. As a result, people whose guilds don't get capped from sheer numbers or raiding sometimes have to choose between doing dailies on a main for guild XP, or playing an alt and forgoing all but a token amount of guild XP.