I'm happier using voltages rather than percentages as you never know for sure if my 95% = your 95%
I just did a quick check on a pack I have here which it shows as '97%' and that one will certainly not charge. If it is turned on and put on the charger you get one cycle of the lights running up then down and it shuts off.
I'll take other opportunities to narrow down what voltage it considers as high enough not to charge but I strongly suspect that there is a voltage limit for all the chargers, but some degree of manufacturing tolerance may determine exactly where it cuts in for each charger.
Balancing the cells is always important, but if you have a pack where it is 'critical' to re-balance at 95% then that is probably a pack you don't want to be using at all
Your point about the 3.0V cut-off is well taken though and is one reason why I've mapped one of the buttons on the back to toggle the battery information. I love the fact that DJI give you cell level data during flight so you can get into the habit of checking for any significant cell voltage deviations before they become a real problem.