Not if you read the item descriptions and do the chalice dungeons, not sure I did get the full scope on the ending but I know after the platinum I had a good enough grasp of the story to draw conclusions and the story definitely stayed with me long after I did plat. Pretty sure there is a lot you'd miss out on if not going for the platinum but it's so long ago my memory is fairly fuzzy.
I did read the descriptions. All of them. It helps you to build the background of the world, just like dark souls. But again the problem os the objectibe.
You start and get the objective "seek the pale blood". No idea what it is or where. And the old hunter tells you you need it to escape the huntera dream. Then you go killing monsters and advancing the game. When you get to Rom you get a new objective out of nowhere, just a message on the screen and things just gets crazier, i will stop here dont want to give spoilers. Its just bad executed.
Again comparing to dark souls... wow... you have a clear objective since the begginning and an amazing story behind the curtains.
But I still love bloodborne anyway.