I mean, I get what you're trying to say, but that isn't really true in scenarios like these. Posters arguing for the "suboptimal" use of cap-space are saying things like the 2.75m cap space used on Kunin could have helped accommodate the 6.375m cap space from taking a dump like Monahan. In these cases, it does take away that exact amount of capspace since it's player-for-player, no 750k deduction needed.
Also, I'm not arguing that that's what should have been done. Simply clarifying the cap space argument.