Virtually no one claims that ground effects have "no business in D&D", most of us are quite aware that D&D has a lot of ground based spells like Spike Growth, Grease, Web, etc. as well as items such as Alchemist's Fire or oil/acid flasks. What D&D DOESN'T have are cantrips that deal damage AND create a surface effect in addition or even on a miss. Of course throwing an oil flask with your rogue and having your mage set it ablaze with Burning Hands or even a Firebolt should remain, no one is arguing that. But a Firebolt that creates a fire ground effect by itself is a bit much, not to mention the general overuse of such effects.
Don't forget talking about dipping^^
Argh! Don't even start with that bull cr... sorry, but, even with all the abstraction, magic and monsters, D&D rules still TRY to stay logical and grounded in reality, and lighting 4ft of steel ablaze with candle is just... yea, it's wacky Divinity fun fun logic, and has no place in any game which takes itself even a little bit seriously.