Part of the problem is that it's quite hard to realistically create "aged data", so running such a competition in a way that actually informs the decision is ha

Part of the problem is that it's quite hard to realistically create "aged data", so running such a competition in a way that actually informs the decision is hard. Mainframes come from a mindset where degradation in performance is something that requires a scheduled maintenance window. Not just for hardware, but also for software. Compare that to the more modern world of "oh we'll just VACUUM the database in the background". The surrounding ecosystem of software might not even tolerate a rare spurious glitch delaying response an extra second. That and all the software stacks on them are huge complex custom monsters, and reimplementing the whole thing from scratch on a more common SQL database is not exactly easy, while maintaining data integrity, performance and not being able to pay Silicon Valley salaries.