The evidence is plain to see that 10 man was easier overall in most fights, WotlK 10 mans were so much easier than 25 man, and that is true for all other expansions, there are a few bosses that are harder but thats mainly because of blizz's inability to tune.
If you dont already have CE then your a casual mythic raider and at this point players would be taking a break anyway as wiping on the same boss for several weeks can get tiresome, WoW is a game ppl take breaks between raids or your going to burn out.
No we need a way to see how good players are, the problem is players that are not skilled enough wasting your time if you have no way to check if they are at even a reasonable skill level, dont blame the tools when its the players that cause the issues.
Its not fun to waste 2 hours or more in a m+ because you have bad players when it could be done in 30 mins, its not hard to learn everything you need to do and not waste ppls time.