how come reviews a few months old are no longer dated?

[Josie2]

I like to see when a guest visited to get an idea of how busy the host was but reviews are not dated beyond a few months.  Why is this? why does the date of stay drop off. Thanks

[Dede0]

I have my theories (mostly involving laziness on AirBnB's part) but I'd also like to know why this occurs. And to request that it not occur. Why not include the dates? How does that benefit anyone?