Yes and no - I think part of that was also that Apple is openly hostile to other app stores on the Mac. It's true that third parties are lukewarm in their support for Mac, but it's very hard to disentangle to what extent that's the effect of Apple's lukewarm support for third parties rather than the cause of it.
Unless you specifically need to target Apple, you don't come across their ecosystem of APIs, which makes it harder to maintain cross-platform compatibility.
Reportedly, Apple is "all-in" on xR, so wait and see I guess. But they're not on the public supporter list of OpenXR for now, as a datapoint: https://www.khronos.org/OpenXR/
When was that? MS Word has been available on the Mac since 1984, Excel since 1985 and PowerPoint since 1987.
Keynote was made because Steve Jobs wanted better presentation software than what others provided that was more like Concurrence on NeXTSTEP.
And Valve not supporting Mac again shows that relying on outside industry is not a viable strategy if you are not the dominant platform. Mac wasn't a big platform for them to sell VR titles as it's not used by many consumers to play VR titles, so they drop support.
As another example, the Oculus client only supports Windows (outside of the Quest etc). There are mac's out there with powerful graphics cards and lots of RAM, however they are few and far between compared to Windows boxes, so Oculus chooses Windows as the dominant platform - If you are going to support one, it will be Windows, and if you are going to support Mac, well it's not going to be the first-class citizen. If Apple wants VR support they are going to have to go out there and graft for it.
The overall point is just - Apple is successful because they decided they wouldn't wait for industry to support their platforms, and that they would just build it themselves if the industry didn't come. For instance, iWork is a direct result of Microsoft not bringing Office to Mac originally - The lack of good presentation software was going to be something that prevented professionals using Mac, so they went out and built Keynote themselves. On the flip side, Photoshop was a great app with best support on the Mac, so they never needed to build a good photo editor. The investments are all to fill in gaps where other people in the industry weren't bringing stuff to the party.