I don't fully understand the grade system

The way I understand it, grades just indicate how much you play since unlike ranks they're not used for matchmaking purposes anymore. If that's the case, then why do we still need pips in order to get a better grade? If you're the kind of player that's never been able to get to rank one, or in this case grade one, but you play consistently enough, then shouldn't you be able to get there regardless of how good or bad you play? Pips just seem kind of pointless now.

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