Rune Concept - Rune Equivalence

This is something I had in mind for a while ever since the Rune Reforged update came out. What if you're able to substitute a Minor Rune in the place of a Keystone Rune?

Inspiration Keystone Rune - Rune Equivalence - At the cost of a Keystone Rune, you may substitute it for ANY other Minor Rune that has NOT been selected from a category of a Rune Path and get a minor additional stat from that Rune Path as well.

I.E. - Primary Rune Path - [ Inspiration ]** | Keystone Rune - [ Rune Equivalence ] | 1st Minor Rune (Contraptions) - [ Magical Footwear ] | 2nd Minor Rune (Tomorrow) - [ Future's Market ] | **3rd Minor Rune (Beyond) - [ Cosmic Insight ]

Secondary Rune Path - [ Sorcery ]** | 1st Minor Rune - [ Manaflow Band ] | **2nd Minor Rune - [ Celerity ]

Stats from selection of Rune Paths - [ Inspiration + Sorcery ]** | **+13 Attack Damage or +22 Ability Power, Adaptive

Third Rune Path - [ Precision ] (This is due to the choice of Rune Equivalence)** | **Minor Rune - [ Legend: Alacrity ]

Bonus Stat - [ Precision ] (This is also due to the choice of Rune Equivalence)** | **+5% Attack Speed

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The problem I see is the impact of not having a Keystone Rune that can possibly affect the game more than another Minor Rune. But in my opinion, this can be interesting as a Keystone Rune choice.