A comment on this anti-Rails rant reads:
Well my application is an online blog post management system with over 1400 database tables and I was pretty annoyed when Rails wouldn't let me use VARCHAR(400) as primary keys. We ended up ditching Rails for PHP 3.2 and I'll have to say I'm so happy now that I don't have to drink the kool-aid of DHH and all these Rails "n-00-bs". Perhaps people should think harder before becoming so arrogant and preachy about things like YAML and Dane Driven Development (DDD).
Ignoring all of the obnoxious bits of this comment, I'll just agree that Railss shouldn't forbid the use of VARCHAR(400) as primary keys. Being competent should forbid the use of VARCHAR(400) as primary keys.