Let me post one example:
I'm defender on a Siege map that is very easy to defend. My teammates and I spam "camp flag" which is easy, braindead, and tactically fine way to win on that map.
What do half of defenders do? They fight on distance walls protecting irrelevant pieces of the map, and feeling satisfied how they are contributing to their team, or perhaps they're just "having fun - dont tell us what to do".
Solution?
Solution is leaving these jokers or zombies alone, joining the server with a bunch of teammates, and winning.
That's what banner balance is for. Banner balance exists so that anarchists and soloers can do what they want on the map, jokers can joke, zombies can crawl around - and people interested in winning - win.
People who like banner balance play to win, people who don't like banner balance don't play to win anyway - so why complain?