Mains feed - bolts or welding

I wonder if it’d improve the output impedance of outlets if the connections on the mains feed line (for example aluminium → copper interjunctions) were welded together instead of using bolts or what have you, for mere tightening.
Cold welding is used in audio cables. Why not have all weakest links in the mains feed, outside & inside, welded?

No sense? Probably not, I’m a bit crazy. Not even a bit.