Quote blocks are embedded, nested structure. Sure seems to me like a punctuation model and a layout model which can understand that, is net beneficial.
I always liked the french <<this is a quote>> model. Somehow it felt more like an embedded thing.
Double quotes have the additional burden MICROSOFT WORD I AM LOOKING AT YOU of the random interpolation of what the editor YES MICROSOFT WORD I MEAN YOU thinks it knows you meant to say. Additionally hijacking the text into badly encoded iso-latin1 or utf-8 mis-parsed, as a free gift.
if I mean to say:
“a quote” (left and right double quotation mark)
I will say it. When I say "a quote" (apostrophe, used twice)
please.. leave those quote-marks alone.(double-dash to em-dash.. same problem: free uplift to UTF you didn't ask for)