In general, the mana curve is higher than average on the low mana drops and that is the result of the many low mana costed Halflings
For that, we have to go back all the way to Urza's Saga, which came out in the fall of 1998, when I was starting high school
In order to push back against the reliance on two mana rocks with a disadvantage like Charcoal Diamond that are heavily played, WOTC has been printing powerful three mana rocks like this pair that tap for any color of mana and then add powerful extras like Decanter of Endless Water
This will allow you to replace all the creatures into 3/3 beasts
You can use the mana to play stuff and hide behind your normal lands and their mana friends for counters and responses
People also arent as aggressive, with the fast kill decks being things that dont produce Prized Amalgams or other bodies that pressure Karn the way they used to