> If you have less than 100KB of JS and CSS (which almost every content site should be able to, most trivially, and almost all should aim to), there’s simply no question about it

Do you have data to back this up? What are you basing this statement on?

My intuition agrees with you for the reasons you state but when I tested this in production, my workplace found the breakeven point to be at around 1KB surprisingly. Unfortunately we never shared the experiment and data publicly.