I also thought this was funny. Because a lot of people tell me to play garen against riven, because riven is someone i have trouble with top lane. A lot of websites list garen as a counter to riven, but its all utter bullshit lol.
She has the ability to trade with you and then instantly dash away before the majority of your E can even hurt her. Garen has no chance of catching a riven if she doesnt want to be caught. Riven scales extremely well with a brutalizer and a last whisper, making your armor useless.
As for people wondering "Why hexdrinker?"
The reason is because the ONLY way a garen is going to kill a riven, is if she is stupid enough to get low enough to let you ult her and die. But if you rush a hexdrinker against garen, it cancels out ALL of his ult damage, making his ult 100% useless.
You would think, on paper, that garen counters her, because he has a silence.
However, his silence doesnt last nearly long enough before her EXTREMELY SHORT COOLDOWN shield comes back up and cancels out your trade.
Not to mention, after each trade, a riven will just take her ravenous hydra to a minion wave and heal 100% of the damage you did to her back, while your still waiting on your garen passive to start working.
A Garen can only outrade a riven in the very early levels, like level 1-4. As soon as she gets a few levels, you will no longer win any trades. And you cannot AVOID trading with a riven when she can literally dash past your minion wave, stun, hit you a few times, and then dash back out before you can retaliate.