That's not what you said. What you said is "I could care less about “alternative browser engines” besides from an introducing bugs and worse user experience point of view." (emphasis mine). So you do care, by your own words, at least in part.
So, why would you care about bugs and worse user experience and not about less bugs and better user experience, which are potentially the other face of the medal when using a different browser engine?
Don't you want to use the best option possible at your disposal? Or you would still use Safari even if a better option were available to you?
About Chrome, I don't even care as I don't use it. I don't even know why it popped up in the discussion.