Nice article and congratulation for discovering merchant which accept
zero-confirmation 
Also, almost-instant transaction confirmation aka
zero-confirmation already used/accepted since few years ago even without SegWit.
It is great to buy things with bitcoin but many merchants are just negative to accept bitcoin due to its volatility. During the last great price drop from 20k$ to 6k$ many merchants have suffered from huge losses due to the price drop. And that is why the number or merchants have decreased and even huge businesses online have started to decline the use of bitcoin due to their losses.
Only applied to merchants who use payment processor or payment gateway but don't choose to sell received bitcoin immediately.