Once other players get far ahead many others will be left out quite literally.
Left out of what?
Certainly, a small core of extremely hardcore players will continue to grind out five or more points a day, and they'll form exclusive groups for Trials, etc. So, everyone else will be left off the top of the leaderboard. But they can still do the content. Assuming ZOS keeps balancing around 'normal' players, and not the top 2%, why would all those normal players be left out? If you can't get in groups with a 500 CP minimum, so what?
It'll be rougher in PvP. But there are already so many gross disparities in Cyrodiil, this is just another raindrop in a thunderstorm.
For a very long time now since the mud days players have complained about how hard it is...