I'm not sure what you mean by there’s "no limit" to maximizing profits. The limit is the point where a higher price causes profits to start decreasing due to decreasing sales/subscriptions. Without knowing overhead costs, marginal revenue, marginal cost, and other factors, there's no way to know what type of impact Apple commissions could have. You can't automatically conclude it is zero.
If they are going to attempt to set a price that maximizes profits, that price is impacted by reduced costs such as not having to pay Apple commissions. Therefore, Apple commissions can indeed have an impact on prices by lowering costs which can allow them to lower the price which can increase sales/subscriptions, and increase total profits. Again, without knowing overhead costs, marginal revenue, marginal cost, and other factors, there’s no way to know what type of impact Apple commissions could have.
Reduced costs, at least a portion, absolutely can and sometimes should be passed onto consumers. Lower costs can allow a company to lower the price such that it generates greater sales/subscriptions profits. It depends on things like price/demand elasticity, price sensitivity, and other factors.