Seefin passage tomb

This is Seefin passage tomb located atop Seefin Hill, County Wicklow, Ireland. The tomb was built circa 3,300 BC. It was excavated by R. A. Stewart Macalister in 1931, but no artefacts or human remains were found inside...

Several theories have been put forward to explain the empty tomb:

Maybe the remains were removed by the decedents of the people who were originally buried in the tomb, when they moved away...

Maybe the grave was, at some unknown time in the past, desecrated, looted, with all traces of the those interred removed and destroyed...

Or maybe, no-one was actually ever buried in the Seefin passage tomb, because this is not actually a tomb...So what was this structure then?

Here is the last theory I heard that tries to explain what the Seefin tumulus was actually built and used for:

Well, you know how all these passage tombs look like bellies of pregnant women? And how entrances of the passage tombs look like vaginas? 

Well whoever built Seefin passage tomb made sure that nothing was left to the imagination...

A very narrow entrance with labia like door pillars and clitoral lintel...Behind this vulva like entrance, just like in all the other passage tombs, is a long narrow passage (a birth canal), ending in a large chamber (womb)...

Anyone entering this "passage tomb" would have been, symbolically, entering the womb of the mother earth...

In there in complete darkness, in complete sensory isolation, they would (symbolically) die...

To be (symbolically) reborn after leaving the inner chamber (womb), crawling through the narrow passage (birth canal) and squeezing through the narrow entrance (vulva) into the sunshine...

Well this is just a theory that no one can prove (or disprove)...It's a good one though...