Attributed points are relative to your teammates’ levels, not the levels of members from other teams.
In a normal team of 50 players, the highest level is worth 125 points and the lowest should be 75 points regardless of specific level. If the highest level is lv999 and the second highest is lv49, the latter will be worth 124 points, gradually decreasing for the rest of the team. The point value won’t be pulled up or down AFAIK…
As for your question why it works like this, I don’t know exactly. It is a rule within a team and the PvP events and I think it is fair for everyone, otherwise certain teams would have an unfair advantage in certain pvp like Gauntlet when two teams are arbitrarily put against each other.
However I’m just a rare quality moderator, I might be completely wrong about my analysis