There are more than 85 Magic sets and expansions, not including supplemental products, spanning over more than 25 years
Again, the announcement is slim on particulars but uses the elite trainer boxes as an example - those will include one extra booster pack and full-art promotional card as a counterbalance to the increased price
Rock - Rocks are not combustible
(prior to banning) Check
It has a low casting cost, it rewards play in spots where you can play tons of cards cheaply, and its shroud gives it meaningful purpose in a format with extremely efficient removal like Fatal Push, Lightning Bolt, and Path to Exile
This is in stark contrast to Modern, where a single staple card like Ragavan, Nimble Pilferer can easily cost upwards of $60-$80, and entire decks frequently exceed $1,000, sometimes reaching $2,500 or more