alt Hacker NewsAgreed. And if deletes are soft, you likely really just wanted a complete audit history of all updates too (at least that's for the cases I've been part of). And then performance _definitely_ would suffer if you don't have a separate audit/archive table for all of those.
I mean, yes, growth forever doesn't tend to work.
I've seen a number of apps that require audit histories work on a basis where they are archived at a particular time, and that's when the deletes occurred and indexes fully rebuilt. This is typically scheduled during the least busy time of the year as it's rather IO intensive.