For me, the difference between this tournament and things like champions or Arbiter skins is that technically 100% of the population can get the latter ones. It is actually impossible for more than 1% of the population to get this skin, because it is impossible for multiple people to get first place in the same tournament.
There is a hard cap on the amount of people who will get this. In theory 30% of the raid population can get Arbiter skins (which were still coming up for purchase for me recently). In theory 50% can get Leorius.
Where are the 30% and 50% numbers coming from?
I would think 100% of the Raid population COULD get the Arbiter skins, if they are willng to spend for it.