It's actually beneficial, mathematically, to find new members from scratch.

Here's a hypothetical: Let's say, for simplicity sake, 16/24 people are available and queued as two parties. Then a 6 man party and a 2 man party queue up. But the 2 man party has one member AFK so they fail to commerce.

If they kept everything there, then you'd only be seeking two people (either a two man party or two individuals). It would also restrict those two as whatever roles you are missing.

So if a full 8 man party queued, or a 5/3 PSU split, or 4/4, or 4 pairs of 2 that don't have the missing specific roles you need, they would automatically be ignored because you're looking SPECIFICALLY for whatever failed to commence.

The current system would just match the available parties to try to prioritize the people who queued the earliest.