Blacklists are an endless loop.
On one hand, it's not the duty of an app creator to apply any sort of blacklist, since in theorz, the community should regulate itself.
On the other hand, though, such "vendor blacklists" are an excellent way of helping it in practice.
Of course, I agree that front-end providers should never enable abuse, not even passively.
I'm not necessarily a fan of big blacklists (which is not to say I'm against them: I'm ambivalent about them, and if someone wants to use a community blacklist I'm not going to give them grief for doing so), but I do think that you should consider who you're supporting when you offer incentives.
I don't think Partiko's bad. My leaving Partiko isn't a moral stance against Partiko potentially creating issues on the blockchain, it's that I hate ads. I'm just adding it as a concern, something that Steempeak doesn't have a problem with because they're not supporting people with upvotes just for making content.