[Pokepokalypse]

I've seen the downside of this. And it's having to have an oncall staff of DBA's hand-grooming fragile databases and running deduplication processes that sometimes get so far behind that it's a mathematical impossibility to catch up with new data coming in. (never mind what happens to your maintenance schedule when you have entire teams focused on "fixing this problem" for weeks at a time).

If it were up to me (and it almost never is, because I'm not a DB expert), I would ALWAYS normalize as much as possible when designing a database. I really can't even wrap my brain around why large (and old) databases ever get into this state. But I've seen it at two different employers and it's very painful (and costly) to deal with. My take was that these databases were probably originally set up by people who had no idea what they were doing, and ended up locking the company into a shitty implementation that kept the company crippled 15 years later. But that's just me.