There is no possibility of a moving chain & steel wedge coming in contact if common sense prevails. I realize that might in short supply.
as stated above, the wedge is meant to keep the kerf open while you finish the cuts, it can then be used to lift the tree over the balance point, but only after the cuts are finished.
if you are stacking wedges, the you will for sure need a wedge in long before you finish cutting enough, the tree will sit back and then you are really hooped.
Should I mention that standard practice is to leave the saw in the cut, until the very last minute, or until the hold wood is sufficiently small enough the any more cutting would be unwise? Personally I cut plastic wedges all the damned time, and occasionally smash them into the saw (a real PITA btw) so if they were steel...
Furthermore, when cutting a hard back leaner, most folks leave more hold wood, so they can get the tree lifted some while they can be sure its not going to pop off the stump, once its stood up you can then nibble at the hold wood and more often then not the compressed wood around the wedges will return some and its enough to tip the tree the rest of the way over.
so if you advocate for using steel wedges, some jack ass is going to try it rip the cutting edges off every link of chain and be in a world of hurt and possibly blind.
Yeah a guy can use a steel wedge when the saw is not in the kerf, but who actually does this? (not any logger that plans on making a living at it) and who in their right mind is going to drag a 7# pound single purpose wedge with them through the woods? (if you say but the truck is only 10' away you can please **** right off).
and no, common sense isn't common, so we should all try and give the correct idea, not the fringe nutter ideas that only work in narrow minded situations.
So I guess there are more then a handful of reasons to leave a saw in the cut, where it could and likely will make contact with any wedge, so not having a steel wedge in the way at all is maybe a good decision?