I certainly agree to a point. We (I) don't have to have the big rotation or limit the blocks for Organized Play discussion again, but at some point they will have to restrict the card pool. Is it now? Probalby not. Is it in another year? Maybe bordering on probably. Two years? Most definately - at that point they will have about twice a normal 'block' of a standard game in card pool and the game gets both unaffordable and unweildly to playtest/manage.
Very few players want to dip their toe in a game and only buy a few chapter packs + core set. I know exactly 2 players like that, and they are both new and have never played in a tourney. But, over the world that might be quite a few people I guess.
All I know is that I have seen multiple potential players be turned off starting the game when they see the sheer size of what they need - that is a valid point to be seen.
That being said, it is nowhere near Magic. Not even close. $500 to get into a game with a tier one game is probably the same as MTG. But in MTG you get that deck (off Ebay singles) and that is it. In aGoT you probably have 50%-75% of another tourney regulation deck, in 3X each. For not much more you can have 4-5 tourney capable decks, while in MTG you need another $500 for each one. If aGoT had a different model, it would be easier to sell singles and you could probably get that deck for $100-$200, but it doesn't which I think is good (you can try out different things, have a multi-player deck, have a fun deck, etc.).