Is it really necessary to limit coveted items to only be purchasable by the Gold tier players?

There can only be a small percentage of players in the Gold tiers, is it not enough that Gold IV players get 9x more bars than Bronze?

Why not allow someone who is willing to put in the investment, the option of working 9 times harder to buy the same reward?

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Bronze 1 receives 630 bars a week, and 5 per round victory.
If they use their 10 tokens for winning every round, of every match, every day of the week they will have earned enough to buy 1 legendary skill tome in about 14.9 weeks.

Someone in Gold 4 doing the same could buy the legendary skill tome in 1.7 weeks.

Is the time savings not enough; Why prohibit the other tiers entirely?