Spell slot value related to action economy can only be understood if you can grasp the big picture. What are the spell value of Fairie Fire? Well, depends on how much advantage you get every single battle. Is it worth using it in BG3? I’d say it’s a bad investment.
Now pretend that Larian remove the advantage homebrew. Is it worth the spell slot? No! Because there’s another homebrew that increase HP values. Meaning that your joe will have to concentrate for more rounds until the foe is beaten.
Ok ok, Sludge. Let’s remove that two homebrew rules as we all agree that they’re bad for spell slots optimization. Now we’re good?
No!! The Joes are throwing bombs and shooting arrows with surfaces that breaks concentration!
You see the catastrophic failure of DnD rules implementation concerning action economy?
It’s a chain of bad decisions in a row for the sake of “ wow, my players do not miss :)”