Riot, There are Around 9,576 Combinations of Viable Runes Possible

And we have 20 rune pages (max) that can't be adjusted in champ select.

There are approximately 90 viable combinations for an ADC, 2548 for a support, 3600 for a Mid, 3675 for a jungler, and 5040 for a top laner. Now a lot of these combinations overlap between roles, which is why you don't see 14,953 in the title, but even so. I didn't even include what could happen if you wanted to split stats from a type of rune (less than 9 of one stat of one rune type). And this isn't just an academic problem; Even if I used all my rune pages just for mid lane, I legitimately could not make enough for all the champs I play mid against common matchups. I couldn't even get close.

Meanwhile, there are maybe 10 significantly different viable mastery pages out there, but we still get 20 pages for those- and can adjust them in champ select.

What I considered "viable":

Marks: AD Aspeed Crit % Apen Hpen Mpen Armor

Seals: Aspeed Armor Armor/lvl HP HP/lvl HP/5/lvl Mana/5/lvl Gold

Glyphs: Aspeed Mpen AP AP/lvl CDR CDR/lvl MR MR/lvl Mana

Quints: AD Crit % Aspeed Apen Hpen Mpen AP CDR CDR/lvl Armor Armor/lvl MR HP HP/5 Gold Movespeed Lifesteal Spellvamp Mana