Ok, I see now. So it only prevents leaking information to outside but the other part still knows everything.

Btw, I think they do support xpubs https://blog.bitwage.com/2015/12/06/new-extended-public-key-import-for-convenient-payroll-privacy/ or it isn't that?

I guess that's my best option to earn bitcoin easily and at low cost (1% of total transferred).