There are two problems with this ridiculously popular but baseless theory:
First, it IS possible to be corrupted by energy from multiple dragons at once. See: Crucible of Eternity.
Second, Malyck has no exposure to the Tablet and its teachings, and still behaves more like a Dream sylvari, or at least a Soundless, than a Nightmare Courtier or a dragon minion. This disproves the claim that the Tablet has significantly changed the nature of sylvari - instead, the Tablet is accepted because it's compatible with the natural attitude of most sylvari.
While I was at lunch with Colin Johanson on Weds, I had a brief chat with Aiden (the EU CM) re: this issue. he stated that the risk of scamming was the main factor behind it, but that if people who had been artists and customers in GW1 could PM me with their experiences (both good and bad) he would make sure this issue was revisited.
Basically, they need to be convinced they wont get a bazillion support tickets about being scammed by artists. So, hopefully given enough examples and testimonies we can change their mind. So while its not a dead cert theu will change their mind, at least they are prepared to have another look.
Ahhh here's an old one from the annals of my time as an officer.
Ok so with many of our guild's members being new to RP we decided, to prevent mary sueing, to roll play. To spice things up we made it so if you rolled 100 whatever action you were preforming became a critical success (beyond what it would have normally done) and rolling a 1 would be a critical failure (complete backfire). Sure enough this ALWAYS happened at entertaining times, but the most entertaining was this...
Ok so I forget exactly what was going on but one of our guild's top RPers and I were going to murder one of our guild mates in cold blood (lol). I won't bore you with the details but going up against 2 rolls he knew he was almost certainly dead. So, he stopped taking it seriously and tried something. He farted. One of our nearby guildmates jokingly said we had to roll on it, so we played along. Here were the results.
Toby (me): 1
Other murderer: 17
Guy who just farted: 100
I could not make this up if I tried. There was so much laughter that we had to pause for a good 5 minutes so everyone could compose themselved. Somehow (Again couldnt make this up if I tried) the fart ignited itself and blew up the room we were in knocking me out and the other guy getting seriosu injuries while the farter walked away unharmed.