Good article pointing out the hidden risk of js-based mining scripts.
I agree with you that using your users CPU power for your gain is bad (unless it's clearly stated with opt-in/out, which is NOT done in this example).

However one minor part of the aricle I completly disagree: "Ad's on the other side, even if they can be harmful, usually don't cost you money."
Ads do also cost you/users in multiple ways:

• your personal data and behaviours (often shared without opt-in, in some cases even private stuff like bitcoin wallet id's together with name and shopping cart content is shared without anonymization)
• traffic!!! sometimes its 10x or more of the size of the content, which is extremly bad on mobile (unless you have unlimited data, but still then it drains your battery) -> e.g. 651kb vs 14.4MB (or 42.3MB after idling) https://twitter.com/marasawr/status/877195379770568704
• huge malvertisment risk which currently also often end up in mining on your HW, but persisistent. or worse...
• also I'm sure soon-ish someone will use ads to deliver a mining script to a much larger audience and profit from it.

at least using a decent adblocker will prevent this, but not yet mining (but I'm sure it will be expanded to those as well in the future).

anyway, thanks for sharing :)