Just imagine what Apple would do to the market if they also offered a full Linux support, but not Windows... They'd probably own some 70% of Linux market outright and also double its overall size overnight.
Don't need to imagine, it did not take off, https://en.wikipedia.org/wiki/MkLinux > Reception was mixed, focusing on the difficult installation process and the significant performance costs of the Mach kernel. Reviewers noted its potential as a "Unix killer", but that it required users to abandon the user-friendly Macintosh experience for a pure Linux environment.
So it was a failure in implementation.