Are you really baffled as you say?

Every dollar Apple would spend on Linux support, they could instead spend on other improvements which makes their products better for much more important customer groups.

Goodwill among Linux people have very low value, since this is a group who doesn't want to pay for stuff. Such goodwill might even have negative value.

And Apple has aggressively been making new offers for these customer groups. Such as their Creator Studio, which is probably hated among Linux people, but a great offer for normal people who need and want to get real stuff done on the computer.