What is the product rationale for not allowing Activity ID (aid) searchable?

Summary:

As we know, searching for activity in OFS/OFFS via Activity ID (aid) standard field is not possible. The doc explicitly states: “You can't use the Activity ID field to search for activities. This is by design.” I am a bit curious and would like to actually understand the product rationale behind this design decision and whether there are technical, performance, architectural, security, or usability considerations that would prevent aid from being supported as an additional searchable activity identifier.

This question is also motivated by a lot of discussions in tthis forum asking for essentially the same capability, including solutions where customers have copied AID into a custom activity property solely to make the value searchable. That suggests there is a genuine operational use case for searching by AID.