this effect surely exists, I myself remember that a younger (XP-whoring) me blindly up-voted such nodes one or two times. (I was a young monk and hungry for reputation ;)

But like proven by eyepopslikeamosquito there is certainly a vote-deflation effect involved.

Selecting nodes from all years best should improve the situation, at least to a point where age doesn't matter.

For completeness (this over-extends the topic):

Other possible selection criteria for other compilations could be :

• the number of links into a thread ( compare google ranking) or
• tags used (unfortunately is the tag-nodelet mostly ignored).