In practise you have a decay system. A score of 2000 a couple of months ago was worth much more than it is today.
So competent players have to keep improving their score in order to be attractive of people of a similar mindset and skill level.
It is usually quite obvious to spot boosted people. They usually just have one of each dungeon completed on a 15 and often have very few or none "middle-range" keys done.
Inviting people or joining keys- just based on people's score is asking for trouble.
The system could of course be improved with automatic logging so you can check people's dps, usage of interrupts, tranq shot etc. But that doesn't seem realistic, even though that would make even more easy to spot the entitled and boosted people.
Added:
Making more information available about players is a boon to people that respect the time and effort of other people, as it makes it easier to find other non-entitled and respectful people.
Making more information available about players is a great hindrance to the toxic, entitled players that want to trick other people in to carrying them.