Comment by mpyne

From the perspective of the one and only app you care about it may improve operability of that app with others.

But from the perspective of a potentially distributed ecosystem of apps and libraries as employed in practice in modern systems, it's actually harmful to interoperability.

Other libs/services/apps that touch the malformed JSON that this change would accept might be present in the overall system and crash on that data. The risk grows with the more components of the overall system that silently accept malformed data and allow the bad data to make its way deeper before it causes issues.

This is what “fail fast” was meant for, if something is going to cause problems in your system at some point in the future, make that “some point” happen ASAP, so that it is easier to identify and fix the source of the flaw.