We dont just pick certain hero to direct-counter-that-hero-in-the-face. Sometimes we pick heroes that can fit in your draft ( 5 man team ) and combo well so you can gain benefit in both aspect.

For example, how often you put huskar in your draft just to counter templar assassin ? That would make ur draft abit weird because huskar is not well-suited in competitive lineup.
We might as well pick venomancer which can act as support as well as the ideal counter for templar assassin.

Just a small example, its too vast. With you picking counter heroes, that doesnt mean your enemy wont counter your counter. So, keep calm and play more dota ! xD