Without a doubt, slang in general hurts a person's communication skills today. People that use slang can't effectively communicate with each other and often results in other people looking down on that person. Therefore, younger people should avoid using too much slang in this day and age to avoid issues.
Young people today are using shortened versions of words. Using different versions of words, or having different words than parents do, has always been something that the younger generation does. But the current one is changing things so that whole phrases might be represented by letters, like TTFN. Communication, such as texting, is more terse. One of the main things that is changing is that kids' spelling is atrocious, due to all of the shortened words.
I think that it depends on where you go in the world as far as communication. In the United States, if you end up in a place like East Oakland or South Central Los Angeles, the locals will speak a form of English that is nearly unintelligible because of slang. But like in other places, they seem to be almost bilingual, able to speak proper English when interfacing with people outside their communities.
I think in general, young people communicate just fine. But with all the slang that every generations young people use, it does make it harder to understand them. I do not think it is a bulk of the young population that communicates in this way. I think that if people want to be heard, and if hey want to communicate to all people, they should use proper language.
Young people use slang to communicate in less time, using letters instead of sentences or phrases. Sentences and slang still mean the same thing and have the same use, to communicate. Slang can do this effectively, because people still understand, just like they understand sentences. Slang is effective for communicating, which is why people still use it. If they didn't, why would they?
Young people today do not fail to properly communicate because of slang. This is because of the fact that although people may be communicating with slang, they are still able to communicate. Successful communication is proper communication. Although there may be less controversial alternatives, slang is still valid communication for young people.