Since solder is such a poor conductor, why use it?

The purpose of solder is to exclude air and thereby oxidation from the joint.

The connection should be first made mechanically and electrically sound, then soldered.

Crimped connections can also be effective in excluding air.

Crimp for a solid mechanical connection. Solder to add strength and rigidity.
That's the way I learned it 40 plus years ago. Hve things changed since then?

Details details. Weld away! There's gotta be a better way. ☝️

Silver solder isn't pure silver - it's a mixture of metals with silver in it. The other metals mixed with it for what is called a eutectic mixture - this lowers the temperature of the mix to a point where it all melts.

And the reason silver is touted as better is that it has the lowest resistance among the elements. Whether the hype is true, I don't know.

One reason not to 'weld' parts together is that that would make it harder to remove the parts in case a repair is needed. Plus, like Czarivey pointed out, high temps would destroy everything.

Timrhu, yes solder is awful now. It cracks.

Joeylawn36111, There are very localized welders that would not influence the circuits.

Almarg, I've learned that too often dismissing the impact of improvements is entirely wrong. Electrical Engineering doesn't know everything.