I've also seen businesses retain "deleted" data in order to support legitimate data analysis work in the future. And it actually can help significantly. Maybe scrubbing PII from deleted accounts is a good idea, but those deleted accounts are perfectly good data points, especially in smaller/newer companies with lower-volume data streams.
If you want to retain anonymous statistics, fine. I'm not keen on you retaining my actual data so you can monetize it after our business relationship has concluded. The biggest thing a small team can learn is why they failed to retain a customer or a trial that didn't convert. For that, usage metrics are considerably more valuable than user data.
