Vanity on Backerboard

I followed the manufacturer's instructions for installing it over wood subflooring. The backerboard seems like it can dent almost as easily as drywall, so I wasn't sure I should put a big heavy thing right on it. My vacuum made a few marks on it so I lost some confidence in its durability. I thought the vanity might sink a little over time and become unlevel.

I will install the tiles first. I guess I was going by the old vanity which was directly on the wood subflooring, but that just didn't seem right for backerboard.

Thanks everyone!