The cost of transmission is partly a factor of peak usage.

Like if you build a highway and everyone commutes at exactly 9-5 then that dictates how many lanes you need.

In places with air-con, the distributed solar reduces the peak on a daily and yearly basis.

Distributed batteries also help with this.

In grid lingo these are called "non-wires alternatives" or "non-transmission alternatives"

https://en.m.wikipedia.org/wiki/Non-wires_alternatives

Having a plan B, doesn't mean you completely abandon plan A.

Would decide against having a spare tire on your car, just because your traditional 4 tires were still required?

That depends on if I have to pay for an entirely separate car to provide backup.

I think there are a lot of valid arguments to have residential solar, but I'm just saying that the big picture economics aren't really there. You have to pay to maintain the commercial transmission and generating capacity, and then pay again for a more expensive redundant local system.

Some grid operators will pay you to have a redundant local system, which suggests the economics do work:

https://greenmountainpower.com/news/network-of-powerwall-bat...