Tea's full of antioxidants. Yes, it does have caffeine, but it's rich in flavinoids and things that improve digestion and reduce the risk of cancer.
Instead of caffeine, beer has quinine and alcohol. Quinine is from the same family of alkaloids as caffeine and has more or less the same effect on the nervous system, albeit a little weaker. Alcohol is bad all round - it depresses the nervous system, it attacks the liver, it coagulates proteins, its poisonous to tissue, it disrupts brain chemistry...it's bad. It's only good effect would be like toughening up the body by poisoning it a little every time.
And if you ever saw what some breweries used to do when making beer, you'd be appalled. In the 70s they used to collect whatever was on the pub floor and put it back into the beer kegs - vomit, cigarette ash, you name it. This was given back to the brewer, filtered, and added to the beer slurry - apparently for texture and flavour. I'm pretty sure that, due to European laws, they don't do that any more. However Guinness still does have a secret formula and a famously thick texture...
