Because you never know what trivial bit of information may ultimately prove to be vitally important.
...and apparently your blog had the answer.
Y'know, I found some loose tea leaves that had to be 30+ years old at my randmother's house. I guess te metal Twinings can sealed it up OK, it still tasted like tea. No medicine required, other than an extra squeeze of lemon...
Yeah, I didn't think tea even had an expiration date. I could see if maybe it had mold growing on it or something, it would be bad, or at least, interesting. But if it's just old, I don't see how anything could be wrong except it might lose some potency in the same way old pipe tobacco gets dried out and loses some essential flavor.
maybe it's some of that canned or bottled ready-to-drink stuff. not like it would lose it's "pop" like carbonated soda.