I'm going to post about Highlander because its got many more examples of cancer things than 6s.
There are few normal scrims that have stuck in my memory for a long time, one of them being against Fair Enough. It was one of my team's first scrims against a Prem team, and we got destroyed. Partially because they were just better, partially because they had people on their team like HartzFartz, who was notorious at the time for running the Beggar's Bazooka, and doing well with it.
The Beggar's would allow Hartz to do 300 near instant damage, shoot rockets without reloading faster than soldier can normally shoot rockets, and do very quick and high bombs, giving him time to load his rockets for 300 near instant damage when he lands.
A few members of my team (myself included) said that this weapon was overpowered, and needed to be banned. We hadn't ever played against a soldier that could tear our team apart like this.
However, over time, playing against good players that could use the weapon well, we learned how to play against it. We just didn't know how to play against it, and we realised that it wasn't overpowered or even that annoying to play against.
Its strange, because we only really found it annoying to play against when we were losing to it, because we didn't understand it.