The stripping I was referring to was of the heads, not the threads.
The bolts you show have circular heads, which you can't put a wrench on to turn them. So they probably have one of the following:
1. Small hex key holes, that you fit small hex keys in. These strip very easily with ordinary hand strength.
At least that is my experience with the soft aluminum bolts that were used to hold the runners on in the old Matrix 1 blades. It helps if you find high quality hex keys that exactly fit the holes - e.g., if you initially need to use a hammer to lightly tap the key in. (Don't use the key for anything else than this!) Then, after a few uses, the holes wear a bit bigger, and you can no longer insert the keys without much play - and it is that play that causes the holes to strip. Then you find various cheap hex key sets, some of which will happen to have slightly too large keys, and you use them. Finally, when the holes have too much play to be used without stripping the bolts (and if you let it go too long, you need special tools to remove them), you need to replace the bolts.
2. Phillips heads. Even if you use exactly the right size Phillips head screwdriver (hint: good quality screwdrivers work a lot better here.), and press down hard as you turn, Phillips heads slip a little against the screwdriver bit, and eventually slip, and very soon strip the head. I know engineers often claim Phillips heads are great, because you can insert the screwdriver in a few tenths of a second faster than anything else, but to me, they will always be a sign of shoddy workmanship.
3. Slotted heads. Much better than Phillips, at least if you can find one of exactly the right size, and once again press down hard as you turn, but they eventually strip too.
4. Torx heads. Likewise. Though these strip slower than the 3 above, but they aren't all that common. So it isn't likely that the roller bolts use them. And like hex keys, they are too small, and eventually strip too.
5. Tamper resistant heads, that require a weird shape screwdriver tip. These never seem to be well designed against slippage, and it is hard to replace the screwdriver or screwdriver tip. Yuck.
I think a stainless steel hex headed bolt really is best, provided there is space to use a socket wrench. A square headed bolt works about as well - but it is harder to find socket wrenches that fit them.
That said, you have to use what is available.