The business plan helps educate the entrepreneur, it helps them prepare for VC presentation, and it helps with some VCs. There at least be a deck; may be a deck and a BP. The details of BP can vary. Sometimes high level is better than details.
Meeting VCs is like going for an interview. You want to prepare for more than what you may be asked.
Having said above, if you get a chance to meet a VC, do not let it go just because you do not have a BP. If the idea is good, the VC would be willing to meet again. At the same time if you are broadcasting to raise capital from VC, then it is safer to have a BP ready.
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