Concern is privacy, not security. Publicly addressable machine is a bit worse for security (IoT anyone?), but it is a lot worse for privacy.
Some of my devices have 1, some 2, and some even more. Takes some precision out, at least.
With ipv4 it can see one ipv4 address
Now sure that 58 could all be on one device with 58 different IPs and using a different one for each connection
In reality that's not the case.
The theoretical vague problem here is being used to defend a status quo which has led to complete centralization of Internet traffic because of the difficulty of P2P connectivity due to NAT.
Firewalls and good old monetisation prevented your p2p connectivity utopia, not nat.
The only difference is most ISPs rotate IPv4 but not IPv6.
Heck IPv6 allows more rotation of IPs since it has larger address spaces.
There are a number of footguns for privacy with IPv6 that you need to know enough to avoid.
On Linux, I think the defaults are left up to the distros so there is a chance of a privacy footgun there. Hopefully most distros follow the example set by Apple and Microsoft (a sentence I never thought I would write...)
No one is saying we should have activated IPv6 in its first iteration.