2 pointsI generally prefer to support the least common denominator to give the users of my website the best experience regardless of which browser they're using.
1 pointI wouldn't say that is true, as new features are introduced Firefox is usually pretty quick to implement them. Also if you have the superhuman power to force everyone to use Chrome, go for it! But! Wouldn't be better to use the option of using the grid-auto-row: and grid-template-row: in this order that will end up giving the same result in all browsers.