Onboarding is highly complex and there are surely experienced developers who know how to do it. I want that there comes movement in this topic. I have the bad feeling that there are no new quality players joining. I don't have the numbers but just because 20 Spellbooks are sold, doesn't mean that 20 new quality players joined. Also, there are now new games like Genesis League .... If the Spellbook is too much for new players (after an increase) they can choose to join the newer Games while their Spell-books are still cheap. This way we create scarcity by making Splinterlands an exclusive club everyone wants to join but not everyone can affort to and then Genesis Goals and then .... So be lucky you were one of the first ones when it was still cheap. Don't wait to join the game.

Now to your question: Why is the Spell-book linked to Starter Packs. I thought this is obvious, but it seems it is not. It just came natural in my mind, but let me think about a proof:
Ok, when a new player joins he has to pay money, obvious. This money (real world like Dollar or digi world like Monero) consists of the price for the Spellbook and if the proposal passes also for packs. Now a link has been established. Buying a Spell-book is onboarding but also everytime I buy a pack I onboard a little bit, don't you think so AZIRCON?