Context is everything. Everything. Virtually every argument in this thread has been about context. Spoken vs. written. Formal vs. casual. Some people have already posted eloquent and cogent pieces that explain where and when these different contexts apply, and therefore where and when objections are legitimate.
Formal written constraints apply to an insignificant fraction of the multiple trillions of words that flood the world each day. The vast majority of those words are spoken, most of them in casual, informal, and personal exchanges. Our brains can supply missing words, replace words that were uttered mistakenly, and even create the context that has been left out.
As someone who has been married over 50 years, I can attest that many conversations with my spouse would drive AI crazy.
What happened to the …
Didn’t you have it before we …
Sure, but then you …
Over there, then, on the other end of the …
Which other end, oh, never mind. I see it.
The written language always has borrowed from and followed changes in the spoken language, although usually with a lag in time. One major reason for this was that most written language had moderators, called editors. Editors stayed within the constraints of style guides, which like all bureaucratic rule-making were issued to lessen complaints from the loudest and most influential. Many, many different style guides existed even in the strictest eras, some written, some impressed into brains by teachers, and some wholly personal. Style guides and editors could exist solely because those who wrote words that the public saw were an infinitesimal segment of the daily word flood.
That statement is no longer true. The vast public has been let loose to write words that any other member of a worldwide public might see. The fraction of written words in the daily flood is the highest since the invention of written languages. Few moderators exist to police these words. Style guides and their tyranny still exist and still apply to certain writers on certain sites. Other transmitters, from message boards to social media to text messages, allow users to be free to write in any mode that pleases them. Many, perhaps most, untrained and never constrained users, tend to write how they speak. People speak differently to different hearers but linguists who record spoken language reveal that ordinary conservation is a loose jangle of words, only occasionally forming any resemblance to the formal language taught in school.
Most of the time this lack of precision is utterly meaningless. True, we all have had misunderstandings, from the trivial to the serious. I’d guess that the majority of those rose from misstatements rather than the lack of precision in the word flow. We are very good at picking up references from a succession of "it"s and experienced in filling in missing nouns. We know that’s true just by looking at memes, which condense thousands of hours of arguments into a few not necessarily coherent words.
I’ve written over a million words for public consumption. I take writing seriously. I’m my own style guide, however. Whatever I write is correct, and my usage can’t be faulted. (Except by me. Everything is written and rewritten.) When, not if, I use ain’t or irregardless I do so with forethought and purpose. I was schooled long before the internet; formality is ingrained in me. I can get irritated by the looser styles prevalent today but that’s about as meaningful as saying that today’s music is all bad. “It ain’t my style” can not and should not be the same as “it’s wrong.”