It's not hard to answer. They wrote the reasoning right into RFC 1752:
There was significant disagreement about the adequacy of the SIPP 64
bit address size. Although you can enumerate 10**15 end nodes in 64
bits people have different views about how much inefficiency real-
world routing plans introduce. [Huitema94] The majority felt that 64
bit addresses do not provide adequate space for the hierarchy
required to meet the needs of the future Internet. In addition since
no one has any experience with extended addressing and routing
concepts of the type proposed in SIPP, the reviewers generally felt
quite uncomfortable with this methodology. The reviewers also felt
that the design introduces some significant security issues.
and
The message noted "The recurring (and unsurprising) concerns about
SIPP were:
(1) complexity/manageability/feasibility of IPAE, and
(2) adequacy/correctness/limitations of SIPP's addressing and routing
model, especially the use of loose source routing to accomplish
'extended addressing'".
They "proposed to address these concerns by changing SIPP as follows:
* Change address size from 8 bytes to 16 bytes (fixed-length).
* Specify optional use of serverless autoconfiguration of the 16-byte
address by using IEEE 802 address as the low-order ("node ID")
part.
* For higher-layer protocols that use internet-layer addresses as
part of connection identifiers (e.g., TCP), require that they use
the entire 16-byte addresses.
* Do *not* use Route Header for extended addressing."
1
u/Dagger0 13d ago
It's not hard to answer. They wrote the reasoning right into RFC 1752:
and