I think the issue is distinct concepts of what a draft pick is.
Some people think that a draft pick only exists if you cut a player to have room for the pick in advance.
Some people think that a draft pick always exists no matter what. However, you might not be able to actually take a player if you don't have roster space. This has always been my personal interpretation, and I've always felt free to trade away any picks I please. I think the other way makes all uneven trades impossible.
Consider the following scenario:
I keep 23 players. Los Angeles also kept 23 players. Thus, before the draft starts I have 2 picks. For argument's sake we'll say I own the 12th overall pick and the 21st pick in rounds starting with round 2. Los Angeles owns the 3rd overall pick and the 5th pick in rounds starting with round 2. (If this looks awkward, this is just how I'm used to picks going, I've only played in the Original J4M (now defunct) and now one of hockeyhead's which is quite atypical.)
I trade Randy Johnson to Los Angeles for their 1st and 2nd round picks. What exactly happens to the picks here?
Before the draft, I was capable of making picks 12 and 45. Now I also own picks 3 and 29, but have 1 extra roster slot. Thus it follows that I will make picks 3, 12, and 29. Los Angeles was going to make picks 3 and 29 before the draft, and that was it. Should I be forced to trade Los Angeles pick 45, as that pick exists, and otherwise they'll be left with a roster hole? Logic would suggest that since I didn't include that in the trade, pick 45 is not going to happen -- a blank pick. I still own this pick but can't put a player on my roster with it. However, even though Los Angeles couldn't make pick 53 before the draft, they still "own" it, and thus I would think they would make their (now only) selection at pick 53. (It won't be the 53rd player, necessarily, as there will be vacated picks, such as my own 45 at this point, but still the 53rd pick in terms of timeslotting and so on.) Do I have to give another team the 8-pick advantage if they failed to negotiate for it in a trade? Seems odd.