Heavy is just heavy, not best. There are multiple things that go into making a turntable good. I don't care how heavy a table is, that will not save a tonearm and cart from airborne vibrations if placed in the room with speakers. Also, it will not help with speed accuracy/consistency.
I agree 100%, and I make a heavy turntable. It is a very, very good one by most accounts, but its weight is only one factor. I suppose time is spent discussing its mass by people mainly because that is what is readily apparent. In my honest opinion, that time would be much better spent on discussing the platter. While there is no single reason why a given turntable succeeds or fails at its intended job, it is a certainty that the platter design and construction is a make-or-break aspect of it.