Why would replaying data for testing be "Delightfully hardcore indeed!". That's how people program in general, they run the same data through their program.
Servers are a quickly depreciating asset, why invest in them?
I don't think they are a quickly depreciating asset compared to the price of renting, but you would want total control over them in this scenario anyway.
But of course you don't have to buy a rack of servers for testing, you can rent it. Servers are a quickly depreciating asset, why invest in them?