i heard swagger jacker back in 05 or 06 when it came out and was totally on the "WTF JAY-Z?!" side of things, but I think it was either Boston or someone... i forget... who pointed it out. The people he knows and respects you can see. But people he didn't like, like Pac, he still respected. In "If I Should Die" on Hard Knock Life, he said he'd run into Pac and ask him where we went wrong. He never wanted beef with him.
Then there's people like Nas "S. Dots on my feet makes my cypher complete" is meant only to compliment the rhyme "I'm not a biter I'm a writer for myself and others/ I say a BIG verse I'm only biggin up my brother/ Biggin up my borough I'm big enough to do it/ I'm that thorough, plus I know my own flow is foolish/" which was only a few lines before. It was meant to make it clear who he was talking to. And a lot of the lines Cam brought up have been used by other artists as well.
What I found out upon listening to Jay a lot more (in the recent weeks I've had almost all his CDs on repeat lol) is that when he does use someone else's lyrics he makes it VERY obvious. He never tries to hide it. He makes it obvious to the point that he actually mimics the delivery of the original lines as much as he can within a song. He wants people to know that a certain line inspired him to write the song or verse or w/e.
So like when Remy Ma said "Like my necklace started relaxin now thats what the fuck I call a chain reaction" quoting almost word for words Jay's line in Money Ain't A Thang, she, like Jay, was just showing "hey that was a sick rhyme that needs to be remembered and inspired this punchline that I thought up." or "hey you're someone I respect so Ima give you a shout out in my verse/song." As opposed to being like "HEY JAY-Z KICKS ASS!" or "SLICK RICK IS THE SHIT!" ya know?
Like I said, it's not something that I agree with or would make a personal habit (even though I have done it to some extent in the past), but it's not something that's uncommon throughout hip-hop. Juelz, Cam's former butt-monkey, "bit" a shit ton of lines as well, so that whole camp is a bunch of hypocrites and actually barely even exists anymore.