Product folks came into existence from hardware teams.
They had a balance of knowledge of engineering, design. These folks eventually led departments. Depending on the kind of company the qualifications will be different.
Now software became more prominent and they required lesser and lesser of manufacturing knowledge. Since software was a layer over the hardware that is built.
The challenge here is now the revert decade of PMs have decided they don't care about engineering. This of course isn't the for all pms. The best PMs I have seen have a good engineering knowledge. They had an advantage that they also cared about users and design as well.
These folks are the best in PMs.
The pseudo PMs want all the limelight but no actual work. Where they think being the middleman in between communication between engineering, design and stakeholders are enough. This is also due to lack of initiatives of engineering folks to pick this up. Hopefully that changes.
So product folks with good knowledge are always required.