They do matter. That's why great care is takem to be pedantic about them. Different cultures just interpret the rules differently. Italians think Americans don't love their families since we usually won't have 3 generations living in one house. Different cookies just do things differently
The social purpose of all those idiosyncratic little things is to be a noticeable enough impact that it keeps people thinking about them and being cognizant of them, and if anything spending a huge amount of effort circumventing them without breaking the literal letter of them amplifies that. Like if it's a constant/frequent presence in your mind that makes it real within your schema, it creates a sort of solid scaffolding surrounding and supporting less tangible belief and making it solid in turn.
This is even more true when, obviously, the rules aren't actually real things enforced by some consistent material power and are instead left up to a group's social conventions or an individual's self-policing. That's where the "light switches count as fire? or maybe work? it's gotta be something. Electric stove coils are definitely fire and work, though," stuff comes from too: their community has decided those things count despite not literally being enumerated by pre-electricity scriptures, and similarly their accepted ways of getting around that problem come from the community as well. So in real, material terms they're not cleverly outfoxing an ancient storm/war god's idiosyncratic demands, they're participating in the shared community standards and practices of their neighbors and friends.