The moderator incorrectly presumed that this was the same as an earlier question. Indeed, it was spurred by that question, but it has a different take. The original question asked what affects fermenting under pressure have on fermentation. The answers were mostly negative affects, which made me wonder why bother. So, I'm asking, why ferment under pressure at all? MalFet's answer brings in other process arguments, not just the affect on fermentation.
The questions are different. I hope they can be unmerged.