I'm European and weigh around 70 kg but a bottle of wine is definitely not a light drink. To me, it's somewhere between medium and heavy drinking, depending on how fast I drink it and the ABV.

You're generalising wildly. I'm from NZ, and drinking an entire bottle of wine sounds pretty crazy to me.

depends a lot on the context too. Over an evening with meals I don't think a bottle of wine is that much. Downing the bottle is another thing

You shouldn't throw all of Europe into one pot. Drinking culture is radically different in different countries, and even in different regions in the same country.