How the English language has changed in 50 years

I came across an article called "9 grammar rules that have changed since you were at school". It assumes that "you" were at school in the 1950s, 60s and 70s (quite rightly, in my case), and the data on the rule changes comes from no less an authority than Brian Garner of Garner's Modern English Usage fame.
As for what consitutes "correct" English grammar, that is of course a subjective and highly contentious assessment, but Garner side-steps this by using a determination of the extent to which old rules have become redundant in regular (American) speech. He utilizes his own five-point Language Change Index, with 1 being misspellings or mistakes that are generally rejected as incorrect (e.g. "arguement" for "argument"); 2 being usages that have spread to more people but are still generally considered non-standard (e.g. using "baited breath" for "bated breath"); 3 being incorrect usages common even among well-educated people but avoided in careful usage (e.g. using "I better" for "I had better"); 4 being usages widely accepted by almost everyone except a few "linguistic stalwarts" (e.g. using "who" for "whom" for the object of a sentence - I think I must be a linguistic stalwart there); and 5 being usages fully accepted by everyone except eccentrics (e.g. using "contact" as a verb).
Obviously, you can quibble with the definitions, and even some of the examples used above, but among the level 4 and 5 changes that Garner has identified as being now acceptable usages, are:

• "None" with a plural verb (e.g. "none of them are mine").
• "Fine-tooth comb" instead of "fine-toothed comb".
• "Graduate from" rather than "be graduated from" by an educational institution.
• "Run the gauntlet" instead of the original "run the gantlet".
• "Reason why" with the redundant "why" (e.g. "the reason why we took the trip").
• "Over" to mean "more than" (e.g. "there were over 400 applicants for the job").
• "Hopefully" to mean "I hope" and not just "in a hopeful manner" (e.g. " hopefully, they will let me in").
• "Dove" for "dived" as the past tense of "dive" (making it consistent with words like "strove", "drove", etc).
• Split infinitives ("to boldly go where no-one has gone before" finally achieves respectability).

It's difficult to argue that these have become almost universally used. But correct? Well... Phrases like, "the thing is, is that ...", "I will be there momentarily", "I must of fallen asleep", etc, are other examples of clear errors that have become widely used, but I still don't accept them. But then I'm a linguistic stalwart, aren't I?