Uh, I honestly don't see a problem with borrowing decks. Someone in the long run did pay for the packs and if they want to let one of their friends borrow it so they have a better chance at winning and stuff, that's fair. Simply because its their right to let someone borrow and if they beat you, its your fault your deck wasn't up to par to beat theirs...though i mean if its like water vs. fire...then obv GG. =\
But Still, people have the right to borrow decks and who's to say that a deck is borrowed just because they haven't played it at your league or something. Honestly, if I had a BOSS deck, I'd save it for a big event and jus playtest secretly on apprentice, and then bust it out at the event.
Also, I have 0 cards past skyridge at the moment, and I don't plan on getting anymore. If I ever want to play again, I'll have to end up borrowing a deck from someone. I considered doing that for the ECSC but I had too much to do around here to go travel 300 miles for pokeymanz. I was tournament calibur and I can be if I wanted to again; I don't see how borrowing a deck makes me much less of a player.
Also, have you ever heard of trading? Thats what you do with the cards you get in the boosters, so you can get the cards you want/need for a deck. Thats what others do to make their 1st place decks.
Also, I know of a few people who straight up bought their decks they used for recent tournies. Some paid well over $200 for all the cards, that's definitely a few boxes of cards right there.
And to argue against your last comma separated sentence =/, I've seen "little kids" play with 15+ decks and still win, so I obviously don't think any deck is set for a certain age, they're set to compete and win you major tournaments if your luck is good.
And to wrap it all up...borrowing is good no matter what(well unless your deck flops). You're allowed to do it, its not a moral sin to use a good deck to beat everyone and get 1st, and if you got the skill to play the deck, then I mean by any means go ahead.
One question though, what if the deck wasn't borrowed that got first, what then? Oh let me answer that. Well "he won fair and square." He didn't cheat at all, so it's fair both ways. Having the cards or not doesn't change your skill level.
Sometimes its the people you know and how much you or they have.