Decktracker = Cheating?

You don't do anything you can't do with pen and paper so it's not cheating.

Edit: dunno what happened to OP.. It's not me. 

That whole pen and paper thing is nonsense, but since it's allowed in the game, it's not cheating.

You can use a pencil to track everything a decktracker does, so, no cheating. Even % of drawing x card can be done with a calc, its not cheating

If the deck tracker is part of the game, why would it not be allowed?

If it wasn't (and it was approved), then I think it is fine, as you can do the same thing a deck tracker does manually.

It's no different if you had a buddy with a list on paper of every card in your deck, crossing off every draw you make every turn, so you can easily see what is left

That's all these deck trackers really do.  They are given the original list of your deck, and cross off any card they see you draw or remove from it.

If decktracker is cheating for a card game, WhatsApp is cheating for life that remembers all of conversations and lets you remember when you open chat log so you can call out some bad conversations after 5 years from reading them from there.

You don't even need a pencil and paper to do what Decktracker does. You can track with your brain, You can count cards, try to remember which cards your opponent plays and how long they are holding those cards etc.

It's only cheating if it shows information you couldn't possibly know without looking through your deck or enemies hand. Like for example. They nab some of your cards and the deck tracker marks the loss of those cards. Well now you know which cards they took and what they have in hand of yours. That's cheating.