Would think the reason for all the washers maybe that was all that was available when repaired by previous owner, "O" rings come in very handy grab kits.
Once you service clean and replace any seals and "O" rings I'm sure you'll have many miles of trouble free motoring.
Try and de grease as best you can too.
The bolt for Banjo would bottom out allowing it to leak,bring in more washers to fill the gap and so on and so on