In the original example, “almost” is standard English usage.
In this context, “most” is an Americanism meaning “almost”.
Both are correct in context. Not all Americanisms are changes to standard English. For example, Americans often say gotten, whereas the English now say got. Gotten is the older form, and is comparable in form to words like broken, woken, and so on.
Unsurprisingly, as this is an example of snobbery, the sort of person who winces at gotten usually also winces at, “It is broke,” or, “Has he woke up?”
In a sense, they are being inconsistent. They should hate all three, or accept all three.
English is an exceptionally versatile and fluid language. Nouns become verbs, adjectives become adverbs, and prefixes and suffixes are added liberally. Etymology is no guide to usage. If you disagree, tell me how far you look through the telescopic forks on your mountain bike.
So-called standard English is only one dialect among many. Even here in England, there are significant differences in grammar, syntax and vocabulary between the dialects of different regions.
That said, I do believe that something approximating to standard English is preferable if you wish to make your meaning very clear. Regional dialects are often simplified, and rely heavily on tone of voice to convey an emotional meaning. A skilled user of standard English can be very precise about his or her meaning whether in writing or in speech.
The challenge, all too often, is to find a reader or listener who is equally precise, otherwise the effort is lost.