Export only low degree surfaces?

In Rhino docs, the ChangeDegree command has this note:

When exporting geometry to another application, make every attempt to keep the degree of your surfaces low. In particular, many mechanical CAD systems cannot import surfaces that have degrees greater than 3.

What does this exactly mean? Like what are these CAD systems and so on?

Hi Jari -

That note was probably added at some point because of some user feedback. We do not attempt to keep track of all possible issues in all possible CAD software, and, as such, we don’t maintain a list of software where that might apply.
Are you trying to solve a specific issue?

I don’t have any specific issue. I’m just curious if anyone knows or has experienced this?