Incoming wall of text below. BRACE YOURSELF!
Before I start this I'll just say that i have no idea what "Raider.IO" is. To me it sounds like something connected with raiding, not m+ success rate.
I have stopped carrying about this "score" mid NH progression as I started to do only the weekly chest run and rarely pug it. As far as i remember, that system was giving you set amount points only for your highest completed key for each dungeon in WoWProgress that is(Wild guess - its same on Raider.io?)
To me this felt like super biased scoring system.
For example I'll use myself - currently my Frost Dk is 973 ilvl. My logic for how one can get 970+ ilvl nowdays is that you are either mythic raider or extremely lucky with titanforging in M+. From my experience, with my recent pugging I did, in 90% of the cases is the former, aka person with more than half brain
So the only reason I could have to decline such person is either I already have 3 dps slots full or I want to make specific setup to have specific tools to use in sone specific pull etc.
But if I try to get in PuG group myself, instead of making one, I get declines always. Why? My wild guess is I have low score on some website. All those mythic bosses kills mean nothing.
A fair score, as I see it myself, should be based on personal performance rather than just one simple "You beat the timer! Gz! Here are your points!"
Currently I play another game, beside WoW, that have multiple trackers - efficiency rating, most damage done, numbers of successful dungeon completes, number of personal kills in that dungeon, scoring based on how much stuff you killed in given dungeon, how much stuff you killed in any of the available specs for the class you play... heck even your individual weapons have tracker how many stuff you killed with that same weapon...
You have so much information that can help you to distinguish good player with just looking at their "armory" than just that lazy scoring that is currently used for m+.
TL;DR - Just one stat to base your scoring system is laughable and anyone who trust such scoring system should not be taken seriously!
If anyone is gonna try to give any kind of rating or score regarding PvE and/or PVP they need to include more stats, or even better said as much as possible stats, so that rating/score will be more adequate in assessing any given player.