A wifi network would likely involve a physical location with security cameras or some trace/hint on the network, although you make valid points there regarding how that could be inaccurate or useless. The individual hiding their own identity in that case shouldn't be the fault of the operator of the wifi, though.
I agree with you that an IP shouldn't, in every case, be your personal identity and that legal situations should take context into account. Everyone from advertisers to the government uses your IP address as a personal identity for you, though. It unarguably leads investigators to your person, and that's our only real method of dealing with cybercrime. Leading investigators to an incorrect individual seems different than to an obvious wall, such as a VPN, that would require a lot of effort and justification on the investigator's part to break through.
Risk-less society in what way, if you could rephrase?
How so? Technically & legally they can find out that the IP address belongs to you / your computer, and will investigate (not that it necessarily means guilt).
I highly doubt that an individual who commits a serious crime over the internet without masking their IP won't be investigated.
Many consumer ISP's use an IP pool, and do not store logs in a tamper-proof way.
Wifi routers are insecure and often can't be flashed with more transparant/secure software, so in practice anyone within 100m with a directional antenna can connect to your wifi.
People let guests on wifi, and students tend to share internet connections.
Some devices randomize their MAC address by default (Apple stuff I think) and MAC addresses are trivially spoofed.
If I'm on your wifi router I can probably spoof the MAC addresses of any and all of your devices, and I definitely can if you've ever connected to an AP managed by me.
Lastly, ISP's can spoof everything and fabricate logs with ease.
So no, technically there is no proveable link between IP address and person or device. Perhaps legally but that has no bearing on the technical reality.
I agree with you that an IP shouldn't, in every case, be your personal identity and that legal situations should take context into account. Everyone from advertisers to the government uses your IP address as a personal identity for you, though. It unarguably leads investigators to your person, and that's our only real method of dealing with cybercrime. Leading investigators to an incorrect individual seems different than to an obvious wall, such as a VPN, that would require a lot of effort and justification on the investigator's part to break through.
Risk-less society in what way, if you could rephrase?