Personally, I think he is wrong.

Several of the features he removed are useful to me. Whatever performance issues he quotes do not seem to apply to my installation.

And there have been rather useful additions to darktable after his fork. For instance the Sigmoid module, an alternative to the author's Filmic module, which I prefer over filmic. Or the very useful Primaries module. To say nothing of various performance improvements, an Mac version that is not broken, and updated camera support.

I've had a few run-ins with the author of this software. He has very strong opinions, and does not accept competing ideas. Good for him to build a fork of darktable that suits his sensibilities. But marketing it as a better alternative to darktable is misleading at best.

I read his efforts as a prime example of burnout. He tried to make the community project darktable into his fiefdom, and failed. So now he's frustrated and angry, and slings insults at the darktable devs.