Are manufacturer AC cables good enough?

There are all kinds of AC cables touted by manufacturers to do all kinds of wonderful things to your sound. The AC plug that all these cables are plugged in to, are fed with regular household contractor grade 14awg cables that go through walls and studs and are stapled to secure them. How would a 10awg cable improve the flow of electricity after it is fed with a 14awg cable run that has many twists and turns and could be 30-40' in some cases. Makes no sense. Can a larger gauge cable clean up any impurities in your house line or allow more electricity when it is only fed with 14 gauge.

I am new to home audio well sort of knew I enjoyed it when I was a kid back in the 1980s. As I got back into it I stumbled on this fight that everyone’s having over all of these cables. I search the Internet to find whatever I could to educate myself on what the difference was between stock versus aftermarket cords. 
I found two things. The first one was more manufacturers than I ever could’ve imagined and none of them had any kind of charts or graphs or information on how they could change your listening experience. It was all words, “like a much brighter soundstage”. What the hell does that mean?
The second thing I found was a guy on YouTube who explains everything in layman‘s terms. His name is Ethan Winer.  He has four or five videos explaining many different things about manufactures and designers and how they do things. Here’s a link to one of his videos. After I watch them and then re-watch them because a lot of the stuff went over my head I never saw the power cord dilemma the same.

https://youtu.be/Zvireu2SGZM
I’ll be interested in hearing what you guys think

Thanks I watched Mr Winer's You Tube video.  Smart guy.
I had a friend over who believed all in science, being that upgraded interconnects do not matter.  He wanted to try his DAC in my system, so we inserted it with his balanced interconnects.  It sounded poorly compared to my DAC (to the two of us).  Then I re-connected his DAC with my Audience AU 24 SX cables.  Wow.  It sounded better (to our ears). Easily.  We switched back and forth.  He was dumfounded that the interconnects made such a difference, as 'science does not support it".
So, if it sounds better (in all the subjective ways) go for it and enjoy!  If you do not believe, that is your opinion, or your science!  Isn't subjective pleasure the basis of our hobby?  

I bought my first aftermarket power cords after getting a PS Audio power plant, the Stellar PP3. First, the cord the PP came with is pretty darn stout. I replaced it with AQ’s NRG4. I got two Shunyata Venom 14s for my Rogue Sphinx amp and DirectStream DAC (Magnepan .7 speakers). I have moved them around and don’t hear much difference between cables, but overall the system has what I’m going to call greater articulation. It’s just clearer sound. I’ve never used the $$$ cables so can’t say. But I suspect the “diminishing return” curve kicks in really, really early once a good conductor, insulator and connector are used. But I guess that depends on your definition of good.

Can someone please help me through the following line of reasoning:
AC current travels 2-3 miles from a transfer station at 220 volts, enters my home into a distribution/circuit breaker box, travels through 45 feet of 12 gauge solid copper wire at 110 volts to a plug in my wall, into which I place a 3-foot long power cord.....
How can this 3 feet of power cord transform the electrons that have come so far into some magical source of electricity for my components?   It does not take much metal-to-metal connectivity to provide 100, 200, or 300 volts into a device.....