Does anyone know why there is a 100K library song limit?

I reached the infamous 100K Apple Music Library song limit some time ago, and have been tweaking my library ever since to add new material. I recently got a new iPhone, and now the Music app won't let me sync the libraries without either deleting songs from the Mac or making the phone library the main library. The latter is not an option, and I have how much damage I have to do to the Mac to meet the criteria to sync. Over 25K songs are purchases from iTunes, which aren't supposed to count towards the limit but do. What is the point of the limit - a 100K library takes up less than 2Gb of storage and I have 2Tb iCloud storage!

This arbitrary limit is idiotic!