How about from the single most authoritative dictionary in existence, the Oxford English Dictionary?
Collecting evidence
The aim of the OED is to provide a record of how the English language is and has been used in writing and in speech. Whether a word is new or long obsolete, its meaning can only be determined by looking at examples of it in use.
The first step in creating or revising an entry is therefore to collect evidence of words and phrases in use from all over the English-speaking world.
Examples of many thousands of new words are collected each year, and we have to choose which of them to include in the OED.
As well as looking out for new words, we also monitor the changing usage of existing words so that their entries can be accurately revised.
They explicitly state that their purpose is to provide a record of use, and they specifically state that meaning only derives from use.
Game, set, match.
Well, I'm not sure of the basis of your assertion about authority inferred upon the OED, but I'll happily defer to the OED in addition to the Chambers Dictionary. Unfortunately, I don't have a copy of the OED, but I have nop reason to doubt the accuracy of your quote. Here's a quote from the Chambers Dictionary:
"But where does so-called 'standard English' fit into all this, the type of English that is supposedly taught in schools? Here the word standard causes problems, because it has more than one meaning. For some, it is 'an established or accepted model', for others, it is 'a definite level of excellence'. The first definition is the one which applies best to so-called 'standard English'. It refers to written English, rather than spoken, as noted by Henry Wyld in 1909: 'The Grammar of Standard English is practically fixed and uniform, so that among educated speakers, no matter how they may differ in other respects, Pronunciation, Vocabulary and Idiom, they will generally agree in using the same grammatical forms'. What he said then is still valid today."
I think this makes me realize that my OP was written in the context of 'standard English', i.e. written English, as opposed to the spoken word, notwithstanding that I did cite apparent misuse of the word 'massive' as spoken by BBC newsreaders to help make my point. I believe, though, that reputable spoken news reporting does, essentially, seek to mirror the same formality as written reporting. You will note that disagreement over written English, as opposed to spoken English, emanating from various posts made on this Forum, was the main prompt for my OP.
Here's another quote from the same dictionary, in the context of changes to written English grammar:
"But can change actually cause confusion? Yes, occasionally. Disinterested ('impartial') is now quite often used to mean 'uninterested, bored'. Alert speakers are aware of potential difficulties, and will avoid problem words. But this leads us back to the need for dictionaries, which chart the multiple meanings of existing lexical items, and may provide suggestions for alternatives."
Now, notwithstanding my general high regard for the Chambers Dictionary, I must take exception to the view expressed here. People who use the word 'disinterested' in lieu of 'uninterested' do so through plain ignorance, similar to the misuse of 'affect/effect', or the 'borrow/lend' example I quoted above (although that, as I suggested, was probably more down to 'fashion' than ignorance for most users, but not all, I'm sure). Is this dictionary really suggesting that 'disinterested' should replace 'uninterested', and, by inference, that 'affect' should replace 'effect' and/or vice versa, if adopted sufficiently widely over time through plain ignorance? I'm not sure, but I certainly disagree with that notion. I also disagree that 'alert speakers' should avoid 'problem words', preferring that they in fact use such words and ensure that their listener(s) understand them, through explanation and education, if necessary (circumstances permitting, of course).
Whilst the author(s) then writes: "But this leads us back to the need for dictionaries ...", the reasons then given therefor do not, unfortunately, serve to overcome the said occasional confusion. It seems that even the dictionary publishers are unsure of their exact purpose and usage!
Maybe some dictionaries set out to serve a different purpose from others. I don't know. But I'd say it was still Deuce!