This is true. The failure modes are simpler. And yes the ceiling is lower as well. Smaller models stability is lower over long sequences. And thus anything that needs a lot of CoT will be weaker. For example, I had a dumb lock + condvar with multiple defenses against lost wakeups in a N producer 1 consumer queue thing. Models generally need a lot of CoT before they realise they can switch it to a semaphore instead. Qwen typically isn't stable over such long CoTs and ends up adding more and more slop and band aids versus a larger model that outputs a large CoT and then realises it can swap 3 functions out with 2 lines if we use a semaphore.