Usually a person have some activities outside of the browser game. Like sleep, eat or even work.
So the bigger the fight points pool, the more time that person can spend on that activities and the more fights that person can get after a long breaking.
After normal sleep capped player have 11 PvP fights when new player have, lets say 5 points limits, which means only 5 fights. After that capped player have 110 minutes (nearly two hours) to refill his points, when the low one must return in 50 mins or he will start to "loose" fighting points. So active capped player always win againts the new one.
And if we talk about bosses - 1 fight with sylvanus gives 140 pts per 20 mins. Energy spending for that 140 pts needs 14 hrs for refilling.