"I have no idea how a pull-through, at any angle could do damage to the crown."
It's called cord-wear in past days in the military, and it's for real. If the pull-through isn't centred well, the cord will be dragging to one side, and usually will be guided into one of the grooves. Once won't ruin a rifle, but the same soldier holding and cleaning the same rifle the same way over long periods and eventually even that slight abrasive action will mess with the rifling at the crown.
As a land Weapons Tech in pre-SARP days we were taught to watch for it. Not as critical with the flash-suppressors ahead of the crown on the FN C1A1 rifles I figured, but it did happen in the old No4MkI*.
Eventually, over time, the abrasive effect will tell, and once it starts it gets worse faster as the cord is guided into the same growing worn spot.
Having said all that, I use bore-snakes in some of my hunting rifles, carefully, especially if I have to pack in or fly in with limited gear.
They get fouled. So; wash them? (Same goes for trouser-snakes, gents...) Dish-soap & water work fine, though you should never ever wash them in a dishwasher... while your wife/girlfriend/whatever is home. (BTW, I meant bore-snakes in the dishwasher, not trouser-types...)
At home & on-range I prefer to use decent 1-piece rods, preferably coated, & always with a guide.
What makes me cringe? Sectioned cleaning rods. Use them if you must, but please at least check them before you use them. I've had some new ones bent, right out of the box. It's as simple as rolling each section on a flat surface a'la pool-cues. Look good? Now; screw some sections together & try again, & see how off-centre some of their joint threads can be.
I'd rather pack in a clean bore-snake on a hunting trip than a bent rod.
My 0.02$ worth...