meh.
Ok I don't generally get involved in highly complex, big project stuff, for which this may be appropriate, however I've often found it way too much hassle to learn a big pile of library stuff instead of just talking to the hardware.
The problem with abstraction is it's yet another layer to wade through when trying to find bugs, as well as a significant increase in the possibilities for bugs to get there, as it adds to the normal list of possibilities, so instead of the typical causes (in typical order of likelihood) :
Bugs in your code
Errors in manufacturer header files
Errors or unclear info in datasheets
Compiler bugs
Silicon bugs
You now have in addition :
Bugs in the in the library code (been there - NXP CMSIS)
Errors in documentation of library code
Errors in your understanding of what the library code can & can't do, or its limitations
You can also get all sorts of subtle issues as libraries grow over time to support new devices with subtle differences that the library writer may not have noticed.
I hate it when even simple examples are wrapped up in all this sort of stuff, so instead of a simple single-file source to demonstrate a feature, you have to dig through a mountain of header files to see where things are defined.
In some cases, this sort of thing can certainly be the way to go, but to claim it as a universal panacea is nonsense.
I also think the whole portability thing is overstated - how often do you actually move a big project to a platform that's different enough to be an issue?
MPLAB Harmony will save everyone using it significant time and effort
Bullshit. Someone using it for an inappropriate application will waste a lot of learning-curve time. Like all tools, the main trick is to decide when you need to use it.
The stuff about "The code is tested, known to work, trusted" misses out a hugely important aspect- it can only ever be tested for specific combinations, environments, loads etc. and anyone who believes thay can just plug it all together and have a working product is likely to get a bad shock somewhere down the line.
IMO it's also at least partly about vendor lock-in, and a "me too" response to ARM CMSIS - learn the Microchip libarries & you're less likely to move to ARM & vice versa.