There's also the plugin ecosystem to consider - ranging from small things you might have self-written or exchanged with other users over the years for your work

There's also the plugin ecosystem to consider - ranging from small things you might have self-written or exchanged with other users over the years for your workflows or to add missing functionality [1], to complete commercial add-on packages adding big chunks of domain-specific functionality. [1] Some of which frankly should just be built-in, but either way it wouldn't make creating a replacement any easier.