Why so many linn lp12s for sale

The reason is obvious. Everybody wants to get the right one but need to sell his own first.

There was some reviewer by Stereophile who kept his first
LP-12 all the time without any 'upgrade'. I myself think
that the platter and the bearing were always the best
parts of the Linn. If one checks how those are produced
one will get 'the picture'. But I hated those 3 springs
which needed re-adjustment all the time.