I think it is nice that we get submissions from older articles that are a few years old every once and awhile. They're healthy reminders of popular articles of days gone by.
At the same time, there seems to be a lot of recycling of older posts going on lately in attempts to grab karma. I feel like this is a too-cheap way to gain these points-- instead of sharing new useful information with colleagues, the system can be gamed by sharing too much of yesterday's useful information.
Flagging something as [old] would be useful -- perhaps some of the folks who've been here for awhile can opt to ignore them a la a browsing interface like /classic/ while still having the option of getting to these useful artifacts if we want.