Your favorite hero...

That's not right. If you don't level up his spellpower, he won't have powerful spells, but overall he's a decent hero, just not the most powerful.

A naive argument. To understand how wrong you are, you just need a basic understanding of mathematics (see the 5th-grade textbook, the topic "percentages") and occasionally check the manual. At the very least, have a general understanding of the race itself. I'm not going to doubt the first point, but you clearly have problems with the second. I suggest you find the "Fan Documents" folder in the game's directory and read everything in it. ;)