Well, now we’re talking about more fundamental issues. Fighters, which are also known as Bruisers and comprise the Diver and Juggernaut sub-classes, rely on closing the gap and sticking to their targets to kill them over time. Peel, which is provided by mobility and crowd control, is the general counter to the class.
When a team groups, its array of peel abilities formidably hinder any champion who would attack it. Fighters who want to access the backline of a grouped team must find either a gap in the zone of peel, flank their opponents, or splitpush. These tactics are not always effective, but a Fighter who has not used his class’ laning and skirmishing abilities to find and snowball a lead should not scale into a reliable, brute-force teamfighter like a Tank, Mage, or Marksman.
With an item or mechanic that could greatly reduce crowd control, Fighters would be uncountered. They could run through Tanks’ and Controllers’ zones, shrug off Mages’ combos, dive onto the Marksman, kill him, and then turn on the rest. In other words, they could literally 1v5 if ahead.