I think you're right there ... synthetics can withstand what would otherwise be considered "abuse" with animal haired brushes.
The thing is, boar is VERY cheap, so to my mind ... does it matter? If the brush wears out from any given technique inside a year, so what? Buy another. It'll be cheaper than most soaps! Boar is good for giving it some welly in a bowl, horse is soft and just tangles up. Short haired boar brushes are great for a good scrubbing face lather. Badger, again, can be cheap at the lower ... and by that I mean the cheaper end which might well include silvertip knots dropped into vintage handles to make a brush cheaper than most new pure badger brushes. I don't "get" the pricing, but if you've bought into an expensive brush, well ... yes, look after it.
Back to synthetics ...
Barbershop style synthetics are a sheer joy to use in a bowl, whipping up a stunning lather ... best use a Builders' Bucket!
For face lathering, I rather like the older generation fibre, like the Kent. I've just put a Muhle silvertip fibre into a small handle which will do nicely, but I still can't get over the feel of my Kent on the face. It "just works". I have a feeling the Plisson (having only felt one, not used one with soap) would make an excellent bowl or face latherer.
But no ... you're not going to damage a synthetic, as such, by using it in what would be considered an abusive manner with animal hair brushes.