All this talk of mandatory maths education reminds me of a weird experiment I was part of in the late nineties: skipping Standard Grade maths & English in order to get a term's head start on the Higher.
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The theory was that the SG coursework element took up a lot of time more or less repeating the same material, & stronger pupils would pretty much reliably pass the Higher anyway so you might as well focus on getting them A's in it.
This worked okay, but backfired a few years later - so I was told, I was long gone by then - in *exactly* the way you expect: surprised pupils with no qualifications in the two core subjects. Ooops.
(For me, the only effect was a delightedly bemused pause at the times an institution puts a mandatory "do you have grade C+ GCSE or equivalent..." tickbox on application forms rather than asking for details.
I mean, yes, there is a strictly factual answer to the question you're asking, but it is not the one either of us want me to say...)