Did Nexon really ban any innocent people?

Yes, from what I read in various places, the majority of people who got banned for "leveling too fast" either abused Bigfoot, partied with someone who was doing that, or bought/sold leeched EXP. Some, however, simply bought 2x cards during 2x events and trained like mad; these people are in the minority, I think.

So yeah, some innocent players got banned. Not many, but some.