I don't think that a plunge cut while felling a tree is a fair comparison to plunging into end grain for "joinery". I've done both and the latter is much more nerve racking, but it is also probably the quickest way to get the job done. The fun part is widening the plunge to allow the 1/2" plate. I understand being hesitant about doing this with a chainsaw, as it requires skill with a chainsaw and understanding of plunging technique.
I wouldn't recommend it for everyone, but a chainsaw makes sense to me.
