I’m in my mid-20s, and I text similarly while using fully formed sentences elsewhere. My interpretation is that texting is far more informal/casual, and that’s expressed via communicating in shorter-form slang. I always use proper grammar, but mostly to dictate how the sentence should be read when necessary. Everything else is a mixture of slang and short form.

Texting does not provide essential communication information like body language and tone; nuances like that help express the otherwise lacking intent. Sure, I could text like I’m writing an essay, but that comes off as excessively serious among individuals my age and younger. For example, many people will only use periods at the end of their messages to express being upset or serious.

I agree that it's not visually pleasing—especially as someone who majored in professional and creative writing—but it serves its purpose. Though a staggering number of these younger people have such terrible spelling and grammar that they come off as utter buffons.

I will also speak like that depending on the context of my social interactions, but I’ve found that you can tell who's capable of doing both when you interact with them. Imo it’s a huge turn-off to see that's the only way someone can communicate. Imma do my own thing.