A question about runes

Is there a reason runes still cost ip and if so what is it? With things like runes getting rebalanced so that one set starts outshining another (flat hp vs scaling) as well as meta changes and just different champions being different (energy runes anybody), owning the right runes has become a very difficult thing. An entirely new rune page can cost up to 7380 per type with 6150 for quints and 6300 for a new page, a grand total of 34590, even for the more dedicated players that is a LOT of ip. And that's just one rune page, considering the number of different roles and builds (ap, ad, tank, jungle, support, etc.) I would argue most players can't afford the optimal runes in any given match. Honestly I don't see what the reason for this is, it's not like it's making riot money (as riots big thing has always been that nothing is pay to win) since you can't even buy runes with rp. I just feel this is a pointless outdated system at this point. And if by some chance there is a viable reason why this system still exists I'd really like to know what it is