Oh, I absolutely agree with the parts telling people not to trust apps that promises free votes etc. But he goes way beyond that to assert that no decent apps will ask for the user's private posting key, or store them. This is just flat out false, as there can be many good reasons to do this. Or at least offer it as an alternative.

The posting key is something you should be able to use more frequently. Else, we may as well not have it at all.