Rengar is still pretty bullshit.
While no, I don't believe he's the op ban that wins games when left open, he's a champion who can get way out of control way too fast. He's a champion who's counterplay is "don't feed him" and that's not exactly a healthy promise when there's 5 potential targets being the jungler.
If I ban rengar its not because I can't deal with him, its because I can't deal with him if he finds my team or myself mispositioned, unlike a lot of champions which I can easily shutdown myself or control the actions of, once he gets rolling there's no stopping with his current passive, in addition to all his new empowered abilities (basically just W) making it harder to catch him.
{quoted}
Since when has the competitive scene ever had an effect on a champions effectiveness/power in solo queue?
It has an effect sooner or later.

But nah, I find rengar's LCS ban pretty big tbh. The fact that LCS ranked teams who are constantly grouped have to ban a predictable assassin just shows how overbearing he is to even peel off their carries. I don't believe assassins had bans or picks in S6 at all. Why nidalee, elise, lee, etc are banned is because of competitive reasons like "they can peel, catch, put objective pressure, jungle control, player's small jungle pool, force team compositions, etc" rengar is banned based on sheer force and power alone.