The only time it is needed to be connected to your passport is at application time and for new passport up to age 20, and once after age 20 and once after age 50. You do not need to update it otherwise and you can travel without that original passport that it was originally linked to. Perhaps the black market thing was over the top so ignore that, but my point it that travel and identification documents without an expiration date are inherently insecure, which makes OCIs very unusual in that regard. I agree that OCI status itself should not expire, but the book representing it should for travel purposes (for which birth certificates generally are not valid). Just like how you are still a citizen or PR even if your passport book or PR card expires.

Any update to the OCI booklet regulations should ideally come along with some regulations regarding the rights and regulations regarding it. This is more political, but it’s clear the Indian government sees it as a long term visa that can be revoked or rejected at any time. OCIs who lived in India but were outside India in March 2020 were SOL until August 2020–India did not consider them as permanent residents who had a statutory right to enter India. Similarly there are numerous cases of people and journalists who were OCIs but were rejected entry into India even when traveling for personal reasons, for allegedly writing or producing something that ‘portrayed India in a negative manner.’