The quote is taken out of context, he’s arguing just the opposite. Everyone has a different 20% and that 20% is an overlapping Venn diagram. It’s almost impossible to find the “right” 20%.
It’s just like the RAD tools - or Java or any of the other cross platform frameworks - there is always something that you need to use that the vendor doesn’t support.
There is no “right”. You build what you want based on what product vision or user pattern you’re aware of and you sell that. You can still build a healthy sized business on it if you tap into the right niche and have gotten close enough.
This space specifically is tough. Figma and adobe products are similarly cheap.