The same is true of military leaders, though - we're just more used to military leaders. You can take the greatest commander in history, and put them in charge of a state that has no meaningful military, and they won't be able to magic up a military on their own. They'd need to take time to build up the infrastructure required for a functional military - they might be able to have some moments of punching well above their weight due to their skill in military matters, but they're not magic. Similarly, there are definitely examples of states that have completely incompetent commanders as leaders who nonetheless have been successful in their military endeavours - even some leaders who are well known for the military accomplishments of their time could arguably be in that list. Justinian probably shouldn't be called incompetent as a commander, but given the pop history understanding of him as the man who re-conquered the Roman Empire, he wasn't exactly a great tactician. I think that all of this can all be applied to a scientist as well - you can take an incredible scientist, put them in charge of a state that has minimal scientific infrastructure and they'll have to build it up to have the state be a scientific powerhouse, while still likely letting the state punch above its weight while that happens. I think the main difference is that any highly skilled military leader has a lot of experience commanding large power structures, whereas most scientists don't - so you'd need quite a bit of training (and talent) there as well.