I wasn't using "Performance" in the sense of "how fast does it go?", but it the sense of "how well does it do what I need to do?"

> Mozilla, Blender, Signal, Android, etc.

First, this is selection bias. I'm sure we can find plenty of cases of software that failed even when designers were around, and I can certainly point to software/services that have horrendous "UI" but were still incredibly useful/valuable: Craigslist and Bloomberg Terminal come to mind.

Second, you are confusing cause and effect. The examples you gave only employ designers now because they were valuable even without designers working on it.

Anyway, you did not address the core point of my argument: no one is going to pay more for a run-of-the-mill SaaS offering because the website was handcrafted.