OK, no standard, hence the need for adapters, thanks!

Mounting plate not cover plate. Pistols that are red dot ready either come with different mounting styles and you may have to screw onto the pistol before screwing down the sight. Here is a link that describes it better than I can.
https://www.optics-trade.eu/blog/footprints-on-red-dot-sights/

Secondly, about this :

“What’s wrong with plates? Well, they start a trend of stacking tolerances and introducing failure points. Additionally, plates add height to an optic.”

I’ve never owned a semi-auto pistol slide milled for an optic, what’s this ‘stacking tolerances’ crap? The one’s I’ve seen in gun cases the plate is simply a cover to hide the hole where the slide was milled, so how does this result in ‘stacking tolerances’?