Export Youtube mixes on a local mp3 file

For the first time I created my own set using Youtube's playlist mixing feature and I loved it! I really appreciated the ability to mix songs directly from Youtube without having the local mp3 file. However, when it was time to export the mix, I saw that it is not possible to create an mp3 file.

Is it a deliberate choice or is it due to technical limitations?

In the end, I was able to create an mp3 file by simply letting the whole set play and recording the audio, but it would be nice to export your mix in the same way that already exists for local files.

This would be very useful when I want to listen to my set in the car where I have no internet connection (or it is very unstable).

Is it possible to do it?