What's the most petty/pointless/pedantic hill you're willing to die on?

Funny; probably the opposite of yours.

Facing the toilet paper outward increases the chance that the paper rips with the roll being in such a position that the loose portion of the roll is lying exactly against the roll: I don't want to have to spin the roll to be able to get to the loose bit. Having the loose bit closer to the wall – probably by virtue of being further away from the user – more often results in it being ripped such that a bit is hanging below the roll, making it easier to grab more often. It's, in total, a much more consistently enjoyable user experience.

Also, less being constrained only to countable objects is an artificial and unintuitive definition. It's not like further vs. farther, describing two distinct concepts which never overlap. Fewer is in reference to counting by individual elements so it wouldn't make sense to apply to things which aren't inherently segmented but it's entirely possibly to measure less of the total of a segmented collection. To say less milk is to take a reduction of the total amount of milk available; this is perfectly feasible with a segmented collection, like cookies. To say less cookies is to take a reduction of the total amount of cookies, something fully measurable and actionable. It is merely that fewer is applicable to a subset of the things which less is applicable.

To argue otherwise is to try and create an artificial construction against the intuitive logic inherent in the natural construction.

I had not realized the latter was a hill I'd die on but, boy, will I, now.