Comment by musicale

That may be sensible if you want or need stronger security and isolation.

However, many companies do support BYOD, especially on mobile where it's a pain to carry two phones around.

There is some support for this. For example, Apple supports dual Apple IDs and separate encrypted volumes for personal and corporate data. Microsoft apps (Outlook) also have some support for separating personal and corporate data.

The benefits of BYOD can include lower equipment costs, lower friction, and potentially higher employee happiness and productivity.