There are plenty of ways to carry extra water without a back bag so "issues" like sweat volume, heat and distance are irrelevant to the discussion.

Secondly, if you lack the basic bike handling skills to ride and drink from a water bottle at the same time, you are a danger to yourself and others. You need to develop those skills regardless of how you carry your water.

So what it really comes down to is whether you find a back bag and a hose in your face to be more or less annoying than carrying extra water on your bike. For me, it's a no-brainer. I'm not wearing the back bag.