If you turn it on at home and it tries to connect to your wi-fi when you do I can pretty much guarantee that your wifi hardware has at some point been associated with your identity and that this will associate that new device with that wifi, using it afterwards on a public/open wifi is likely to make the same association available(to whomever may be in a position to see/find/use such things).

Also MAC address isn't the only hardware identifier in any given device, just the one publicly advertised/known...

If it is easy to hedge ones bets, why wouldn't one do that when one doesn't know with absolute certainty that one can stay anonymous, all it takes is 1 time and then it's too late...

If you turn it on at home and it tries to connect to your wi-fi when you do I can pretty much guarantee that your wifi hardware has at some point been associated with your identity and that this will associate that new device with that wifi, using it afterwards on a public/open wifi is likely to make the same association available(to whomever may be in a position to see/find/use such things).

Also MAC address isn't the only hardware identifier in any given device, just the one publicly advertised/known...

If it easy to hedge ones bets, why wouldn't one do that when one doesn't know with absolute certainty that one can stay anonymous, all it takes is 1 time and then it's too late...