There is a time management component to this. If you're still in a deal without a 27001 certification, the security questions don't go away. Instead, you get sent a security question set to answer. These question sets can be huge - our record is about 300 - 400 questions. And once you've answered those, you're not done - then you go into discussions with their cybersecurity about your answers.
Once you're in the loop with a number of large deals, this becomes a huge time sink.
And no, you can't give this to an intern, or just search-and-answer most questions, because every company formulates their questions and requirements differently and it takes some knowledge to figure out what they mean and want.
And at times the discussions afterwards are even worse. I've had InfoSec-guys tell me they're concerned because I cannot give them the specific details on the physical security of an AWS datacenter because these are not available.
As much work as getting and maintaining an ISO27001 certification is, there is a point after which it'll save you time and nerves.