From a designer point of view (and by that I mean someone who understands and can handle CSS -- not the type of 'designer' for example the Elementor marketing team seems to have in mind) I welcome every way and opportunity to disable Gutenberg/Block Editor features that offer design options, be they automatic (like that new gap thingy which is at the core of this thread) or offered by interface, like color options and such in the block options panel. I am very glad that in my themes I can at least by now control the color options (as an example) through the theme JSON file, and I am maybe just to blind to have yet found an option to entirely get rid of it, or any design related interface in the editor (I hope there will be an easy way, eventually). I love Gutenberg aka the Block editor, but I love it for the gift of easily building structure. I prefer to literally entirely control the layout through the style.css. Of course there are tricks, like dequeueing the core style sheets, but it would be so beautiful if there was a universal opt out option for anything design that is delivered through block editore core functions. As for the top margin, to be more on point: it is something, I never ever would do to get spacing above an element. I would always add padding to the element or a wrapper. So, regardless whether that is good or bad practice (I don't believe, btw., anyone could convince me that it is a bad practice), I should be given the possibility to keep using that approach in designing my themes. Denying designers an opt out seems to me almost an arrogant approach from sides of the WP/Gutenberg dev team. Just my five cents, no offence …