Relative safety of skiing in the trees

In avalanche class last night, one of our instructors taught a point that I've heard repeated of late.  It was to the effect that if trees are wide enough to ski through, then they provide no protection from avalanches.  I tried to question the nuances of this but was probably not very clear so didn't get a good answer.  I understand the point that an avalanche could occur in any tree stands except those that are exceedingly dense, but it seems like trees must provide some relative protection as anchors of the slope, even when more widely spaced?  If there truly was no relative safety in skiing in trees, then all other things being equal (slope, snowpack, elevation, etc.), then it seems like you'd always be safer to ski on a completely open slope, because at least then you wouldn't have the hazard of being strained through the trees if a slide did occur.   Don't most skiers ascribe some protection from avalanches in treed areas, though? This of course could also be due to a generally safer snowpack than in open areas (less potential for hoar frost, more shading) but seems intuitively related to anchoring of the slope, as well.

Certainly there are situations where even in the trees you are unsafe from an avalanche.
I have been in avalanches that are in the trees.
That is why those classes are pretty good as a starter to get an idea of the potentials of what avalanches can do, but NOTHING can match experience on the hill.
I have seen where snow is avalanching down a treed run and the billowing plume is 20 feet in the air. That was when snow was hyper-reactive in the eye of the storm when accumulations were over an inch an hour. Steep rollovers in the trees can start things moving. Or avys from above can consume a slope and grate through the trees too.
Continental snow is a different beast too and it does not settle as quickly as PNW snow. Think Utah blower powder that can sluff real fast and gain some steam rolling through the trees. There is so much snow in the air that one can aspirate it and choke. I got caught in a slide in the trees in Utah several years ago. It was like being in car wash of snow.
For the most part you are in a better position in the treed areas vs the open slopes. You need to evaluate that on your own. I have safe skied slab snow in the trees too. When you gain more experience with the snow conditions it is possible to find a safe place to ski in nearly all alert levels.
I don't see a lot of propagation in the tree skiing that I do, but certainly I would not exclude it from my awareness.

I'd agree with Joe -- it depends enormously on the conditions at the time.  Two brief anecdotes:

The three Crystal snowboarders (may they rest) were hunkered down in a thick stand of trees for the night when the open slope above them slid, top to bottom.  It probably flowed through 50-100 yards of treed terrain before it covered them, then continued down the hill.  Took out some timber.  So... make sure you know what's above you.

Second one -- a friend of ours was cat skiing in eastern BC, skiing a treed run that the guides had never seen slide.  This friends was the last of 12 (or more) skiers to ski it, on their 2nd or 3rd lap of this slope (think upwards of 20-30 tracks on slope).  The slope ripped out and the skier was funneled through the trees.  Excellent first response care and rapid transport, plus months of recovery, and the skier came out okay.

So yeah, it all depends on the conditions, but if it's steep enough to slide, it might, whether there are trees or not.  A good point to remember, for sure.

Depends on how you define "protection" from avalanches.

Other things being equal, trees can offer anchoring effect, protection from radiant heat, shielding from wind loading and surface hoar formation, and something to hide behind. On a given day, that could be a factor in choosing where to ski.

On the other hand, they present a very hard surface to be pushed into by a large quantity of snow, and as pointed out previously, do nothing to affect the stability of the snow above them.

Part of the perceived safety in trees is that given a slope with both open avy paths and treed sections, you are safer in the trees. It doesn't mean it won't slide or get hit from above, just less likely than a known avy chute.

....one of our instructors taught a point that I've heard repeated of late.  It was to the effect that if trees are wide enough to ski through, then they provide no protection from avalanches.

I have been told this as well. During higher avalanche conditions I often ski treed slopes... typically a densely forested location steep enough and wide enough to ski thru... that are not below open avalanche terrain and places that I feel are safe in most any condition. It's been my observation that in some locations I would guess it has never avalanched and probably never will, but I don't want to let my guard down...

What are the conditions that could cause an avalanche in such a location? Are there terrain features to be aware of in said forested locations that could promote avalanches?