The big problem with Apples professional lineup is it's lack of GPU upgrades and power. Along with supporting the GPU manufactures by adopting standards and improving them.
I'm tired of them and others blaming intel. x86 is no longer where huge increases in computing power will really come from-- we all clearly see this due to the laws of physics. Parallelizing computation for all its problems, is the future, and GPUs are dominating in this area. From video rendering, machine learning... and I'm sure most of us would drool over a web server that could use a GPU to speed up requests or a compiler that would use it to speed up compilation.
But GPUs are "not apple," because GPUs are not thin and need to be replaceable. This is antithetical to their whole desktop division.
This glaring blind spot is one of the many reasons I'm a depressed mac user these days. If I want to do cutting edge things, I cannot do them on a mac. Imagine how good the new MBP would be with a GTX 1080 in it? Or a Mac Pro with two Titan X Pascal cards? A Mac mini that supported even one full size graphics card. The iMac? Well that's a relic (in my humble opinion) but the all-in-one does still have a niche it serves.
Also, the fact Apple continuously and blatantly ignores gaming on the Mac this will likely be true. Because gamers also upgrade more aggressively than most desktop users and they help drive innovation as a result. Gaming on the Mac is still a joke. Ports are often late, poorly done, and underperform compared to their PC brethren. I'd rather game on Linux than Mac (no offense to my Linux using brothers and sisters) but I think that's crazy.
I said this once before. What Apple needs to do is make the mac lineup based modular components. E.g. "Here is a box you can slide a video card into ('made for mac if course' with approval to make sure driver hell doesn't happen like Windoes) it then can fit into a Mac mini, iMac, or multiple of them into the Mac Pro. Same for PCI cards in general. This then makes things more user friendly, power users then can upgrade again, and the 3rd party industry can start making for mac.
There are plenty of other ways to innovate-- I'd love a dual socket Mac Pro like the old G4 towers. M2 support. Not looking like a trash can (okay I'm just being cheeky now so I'll stop)...
It's not that innovation can't happen on the desktop it's that Apple isn't, to use their own words, "brave enough to."
... What happened to the crazy ones?