A. You can turn off the filter
B. Age really doesnt have any relevance in this game
Especially on point B, you have many 18+ year olds acting very immature. Hold on that thought though. What is so abnormal about an 18 year old being immature? 18 year olds are adults that are fully mature now? They don't think they're invincible and 90-100% right in most if not all situations despite having little to no real experiences to warrant such claims? If you have people telling you to stop using offensive language you're more likely than not speaking with the better half of the community that actually represent mature individuals in society.
Using a crude 4 letter word in every sentence, being condescending, abnormally critical and hypocritical does not equate to maturity in any sense of the word. Also the chat filter isnt useless, half the time people say something in their broken sentences and it's filtered I barely give myself any time to decipher the stupidity. If anything it makes thier insults an eyesore and helps players ignore them.