For the first question, you might find answers more helpful if you ask the aforementioned people that you’re actually interacting with.

And regarding the second question, it’s probably related to the first. Young people who grew up texting and using social media have adopted abbreviated writing styles. Older people using the same technologies tend to retain more proper forms. Of course, people aren’t monoliths. There’s plenty of young people writing in complete sentences and plenty of older people utilizing short form words.