It can include graded cards of all sorts, & rare vintage cards from early Wizards of the Coast (1998-2002)sets and more
Constellation Whenever an enchantment enters the battlefield under your control, you gain 1 life
According to the PSA grading standards, a Mint 9 is "a superb condition card that exhibits only one of the following minor flaws: a very slight wax stain on reverse, a minor printing imperfection, or slightly off-white borders"
This is important for all decks but particularly important for aggressive ones, which need to be racing and not stalling (or at least, knowing when to race and when to stall)
Easier Buying, Selling, and Trading Graded cards are significantly easier to list and sell on platforms like eBay, Vinted, and specialist trading card marketplaces
The same is true for cards like Hushwing Gryff and Reckless Bushwhacker