If so many consider the apostrophe so complex and confusing to the extent some grammarians are now advocating we abandon its possessive form then for the life of me I cannot see how we can expect more complex rules such as the I before E, except after C with its many exceptions ever to be understood by everyone.
Both the greengrocer's apostrophe (pl: DVDs not DVD's) and the possessive form of the apostrophe are about the simplest notions one can learn in English.
Yes, these rules have nuisances but I'm not referring to them but only their most common simplest forms. (By that I'd exclude unusual forms such as whether it's best to use 'greengrocer's apostrophe' or 'greengrocers' apostrophe' or that it doesn't matter. Or whether three 'Ss' should be used when using the apostrophe such as Kiss's Building — the name brazenly embellished in the frieze on a building near me.)
My marks in English at school were rarely ever much above pass grade but even I had no difficulty in understanding the possessive apostrophe. In primary school we were taught this simplest of rules by just asking "who owns it?" then drop in the apostrophe immediately thereafter.
Q: Who owns the bat? If only one boy owns it then the answer is "It's the boy's bat." If multiple boys own it then "It's the boys' bat."
I cannot think of any rule much simpler than this, same with the greengrocer's apostrophe where just adding an 's' sans any apostrophe is similarly straightforward.
It seems to me that teachers of English ought to actually learn to teach as they did when I was a kid.
It's clear to me we need to bring the population up speed on the basics before venturing into esoterica, for all but the cognoscenti the Oxford comma can wait.