Innocent until proven guilty is a mantra used when determining if the state can deploy violence and curtail your liberties, e.g. by physically confining you in a prison. It's not a universally applicable rule, and isn't what's used in civil court, where judgements are made on balance of probabilities (i.e. if they think the evidence suggests it's more likely that you've done something than that you haven't) and isn't what's used in contexts other than the legal system, like when a duty of care exists - generally it wouldn't be enough to say someone was safe to work with children if they were only probably not a paedophile.

It's my understanding that there isn't enough knowledge available to the public to exhonorate Snoop Dogg, and without that, he's left looking sketchier than he was before. One dropped allegation could be nothing, or the start of a pattern, and that's different to there being no allegations at all.