I recommend Franz (http://meetfranz.com/). Does Whatsapp, works on Linux, mac, pc. Supports Slack, WeChat, HipChat, Facebook Messenger, Telegram, Google Hangouts, GroupMe and Skype.
I think you're reading a bit too much into his comment. It's true that the phrasing can seem dismissive, but I don't think it's meant as such to that extreme of a degree.
It being a collection of wrappers is either true or not and is not necessarily a value judgment, but a technical detail.
Wow that's cool. This seems to be the spiritual successor to Adium (maybe Pidgin, not sure if that's still active).
Edit: Tried it out. It's visually pretty but it wouldn't even let me add my Slack account (we use SSO, maybe they haven't updated for that). And then when I clicked the Send Email to Franz, the email was prepopulated with some social "download franz!" message.