Prestige Skins and "Events"

I recently bought the 1650 RP (about 15 bucks) arcade pass in order to grind for an older prestige skin, prestige battle academia Lux. While on the grind though, I noticed that the prestige points store had no contained the skin I had wanted. That being said, I looked up online and Riot had iterated that there are "event" prestige skins and those that could be bought on the prestige store. Wouldn't this destroy the whole point of a "Prestige" store as the whole point is to buy Prestige skins of the past? Why wouldn't an "event" prestige skin be incorporated into this store when a lot of players don't have time to grind in a certain month compared to others who do? It seems very unfair to me, especially since Riot failed to reiterate this. I wish I would've been further informed about buying the pass, now there are no refunds available for a skin I can't even grab. Now my 1650 RP had just gone to waste...