Genuine question....

I'm 30....I don't consider myself old but I guess I am in some people's eyes!! One thing that I really can't understand these days is why people who are younger than me, put loads of letters in their words when they type. For example - cantttttttt wwwwwait to go out tonightttttt!' Or ' so saddddd todayyyyyyy' or 'AF is lateeeeee' I genuinely don't get it. I'm not approaching this as a bitch, just curious about why? When I see writing like that on social media or in this app, in my head I always imagine the person having a stutter or a drawl or something!!!! 😂