There are as many ways to collect as there are individuals. In the video, Petruzzo was quite explicit in descibing his method and saying that "this is called the upgrading method of collecting" - recognizing that it is one method among many.
Brasher is vintage purist to the extreme that if a bulb burns out on his layout, he doesn't put in a new bulb: he has to find a vintage 1920's bulb that's still good, to use on the layout. That's awesome! And, it definitely wouldn't work for me!
So you find the method of collecting that works for you, that gives you satisfaction, and you enjoy doing it that way. And you listen to others describe the way they collect, and realize that their way gives them satisfaction too.
The other thing to realize is that your own method will undoubtedly change over time as you learn. Over in another thread, someone just wrote a very clear post on why they aren't interested in old vintage stuff, the new reproductions are dependable, look great, and are less expensive. I had to smile because that was exactly my position several years ago, and for the same reasons. Now, a decade later, I'm surprised to find myself gradually replacing my MTH trains with vintage Ives, Dorfan, and Flyer; and MESG - two areas of tinplate that excite me. And the reasons - dependability, appearance, and price - are not at all as obvious as I thought back then. Funny how that happens.
For something like the issue of "upgrading" by trading out parts of sets, and even parts of cars, to gradually upgrade your collection: you just have to decide whether that way of going about it will bring you satisfaction, or whether you'd rather do it a different way, and let someone else do the upgrading. Since that person is always buying and selling to upgrade, they might become a great source for things you're looking for, even though you don't have the same objective.
A big collection coming up for auction is the result of one person's approach to collecting. You don't have to agree completely with his method, to value and appreciate his collection and what he did.