I actually can give some examples.
I've never been able to make a bow in 30 hours of play. Why? I've only come across one sinew. That's it. Nobody sells it. I haven't found anymore after plundering every crate and barrel I've come across.
Now again, I can't complain too much because the bow I have equipped is fine, but.... I did save scum with one of the merchants in Cyseal (fletcher? enchantress?) and she went from selling sinew to out of stock upon leveling. Unfortunately I didn't grab any the first time, went out and leveled up, saved near the merchant and saw they had no sinew. Reloaded and still nothing. Needles were also nearly impossible to find.
I mean it's one thing if the item is supposed to be rare, but this isn't the way to do it. It doesn't make sense lore-wise - so that doesn't excuse it away. It makes my playthrough unique..... In the fact that I couldn't find utilitarian crafting items. There's no real in game economy or trade.
So the point is what?
All of this rigamarole for simple, basic things is crazy.
Because the next time you play your experience will be different. This time you encountered a paucity of sinew in your adventure leading you to rely on bows you found as treasure.
What makes it a strong design decision is that none of the randomized elements can ever prevent you from completing the game. You just feel a compulsion to have total freedom/access to every detail as you feel the impulse to do it. If you don't obsess over crafting a bow and just play the game it definitively wouldn't matter. Check the various shops after you level and remember which ones sell crafting goods.
This game doesn't reward obsessive compulsive style gameplay. It intentionally subverts those playstyles in an attempt to get you to think differently about tactics and your decisions in the game world.
In the kindest words: The game isn't broken, you're trying to play it incorrectly.