Yes, it is how you say. Top pvp players have much more opportunity to upgrade their legends.
However, they earn their coins by being active in pvp and beeing at least over average in their skill level. You also have a bit disadventage as a new player as you can expect the opponent ladder player to always have potentially better Pokémon than you. Anyway, its their reward for beeing in ladder so many times. I dont see a big problem there, there must be some reward for the top player.
As mentioned its not like its impossible to get rerolls.