Tea is a subject which is meant to be taken and faced head on. That is to say, tea must be drunk with no additives other than the tea itself. Tea contains many complex flavors, and each must be individually tasted.
Take tea with milk as an example. Tasting it, one removes all airy and oaky flavors from the beverage, and this isn't even counting blends, green teas and herbal teas. Now, take tea with sugar or, alternatively, honey. Well that eliminates complex patterns of bitterness. For you see, the bitterness in tea hits you in light waves, if steeped properly. It is an accent which allows for the airy and oaky flavors to then come in and relieve the tongue. You see, to add these things is to destroy the integrity of the tea itself.
There is then the argument of Chai Tea, which arguably tastes the best when a dash of soy milk is added to it. Well in this case what you are doing is adding an additional accent to the tea, rather than overwhelming it with another flavor. Insodoing you are in fact aiding the tea's flavor rather than destroying it. On the other hand the complex palette that Chai Tea has when alone is somewhat forfeit in this battle. It's something that Tealitists have been discussing for the better part of the last century.
Tea is a wonderful beverage full of a complex palette of flavors. To add one's own is to stop calling tea. So says a Tealitist.