[ghaff]

It's one of those pieces of advice that is hard to say it's wrong exactly. However, for many professional employees at a great many companies, it's pretty extreme as practical advice. There are some sensible practices like keeping work email and personal email separate and, for both your own and work devices, following whatever infosec policies there are around encryption, VPNs, and so forth.

But, in general, never do X advice can be actively harmful because it advises people against doing things that very many do without repercussions and causes people to ignore advice that it's important to follow.