They're not strictly necessary, no. In fact, I would highly advise against a live roll at the table, as you can have items turn up at very unsatisfactory places. It's best to rig the deck, don't tell the players, and have things happen where the DM choose, so you're catering the story the way you want. Also, the number of options the deck provides is overwhelmingly too many, as if someone is going to run this adventure 5 times for 5 different groups and always wants something new. I highly doubt that will happen.
We are playing in Roll20 and I simulated a table, put the cards I had created in the GM layer and had players say "I will pick a card" and I made some stuff up about Madame Eva shuffling the deck and laying down a card. They never knew it was all meticulously planned. I even turned Pidlwick 2 into a little evil ally to find in Vallaki and what was in the deck, rather than leaving him in the castle until way, way late in the campaign.
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