Because whats the point.
Pikachu A caught in viridian forest
Pikachu B caught in pallet town.
Both identical stats: Whats the difference?
Only the location
Does it affect anything?
No
Well, I think it would matter in order to recognize event Pokémon.
As GF has the power to make pokemon considered illegal (for example a magikarp with hydro pump and yes they did make one, or a pikachu with surf ) They could even slap an ability to a pkmn they aren't supposed to have.
That's where location, how it was obtained, the pokeball and the abilities, or ID is important, basically to make said pokemon legal with their . As it is easy for a noob to just try to create the same event pokemon, slap the same moves and abilities and ignore these terms. Thus, it would be 'badly hacked' and illegal.
While it might not matter much in the competitive business as you say, I guess it could matter for bragging rights.
Hell I don't have a pikachu with surf (but I could make one) but if my opponent does, I certainly wouldn't expect it.
But yeah, if illegal moves, illegal abilities or illegal stats are stopped, it doesn't matter much if u think gameplay wise.