If the ARRL had gotten its way in 1963, Generals would have lost ALL phone privileges below 10 meters. That was part of the original ARRL Incentive Licensing proposal. I'm willing to bet, based on what I've read in ham magazines from that era, the league thought they could ram this through the FCC at will. Fortunately, the FCC shot it down and created the compromise that took effect in 1968.
You're mistaken. You've left out WAY too many facts. For example, 160 was never part of incentive licensing.
Here's what REALLY happened:
1) Before mid-February 1953, Generals and Conditionals had NO 'phone privileges at all on the bands between 2.5 and 25 MHz. To use voice modes on those bands required an Advanced (old Class A) or Extra license. Generals and Conditionals could use CW everywhere on those bands.
2) In mid-February 1953, the FCC completely reversed that policy and gave full privileges to Generals and Conditionals. This meant that four of the six license classes back then had full privileges, and there was no operational reason to go beyond General or Conditional.
3) The original 1963 ARRL incentive licensing proposal was simply to reopen the Advanced license to new issues and return to how things had been before the Great Giveaway of 1952/53.
4) Under the original 1963 ARRL proposal, all a General or Advanced would need to do to get full privileges would be to pass the Advanced written exam. No additional code tests, no experience requirement, just one 50 question written test.
5) Under the original 1963 ARRL proposal, the loss of 'phone privileges would be phased in over a period of years so that existing Generals and Conditionals would have time to study for and pass the Advanced test and upgrade before losing any privileges.
6) Then as now, FCC would not make any such change without formal comments, reply comments, and other steps. No group could "ram through" any such changes without everyone having a chance to have their say.
7) The original 1963 ARRL proposal caused others to write proposals - at least 10 other proposals were sent to FCC and given RM numbers. There were thousands of comments filed - and this was back when there was no internet, no word processors, and even things like copy machines were very rare.
8] The end result was a conglomeration of changes that went into effect in stages starting in 1967. Nobody lost privileges until November 1968.
What drove "incentive licensing" was the
perception that US amateurs were falling behind, and becoming nothing more than "appliance operators". The early 1960s were a time when the Soviet Union was ahead in the Space Race, when JFK asked that we face the New Frontier, go on 50 mile hikes, join the Peace Corps, etc., when schools got the New Math and enhanced science programs. Amateur Radio was not immune to that
perception.
The reality was that the introduction of the Novice license in 1951, plus post-WW2 prosperity, military surplus, the growth of the suburbs and the middle class, and developments in electronics had resulted in a rapid increase in the number of US hams. At the end of WW2 there were maybe 60,000 US amateurs - by 1963 the numbers were four times that many. These factors also led to most US hams building kits or using manufactured gear rather than homebrewing or converting surplus.
Most of all, the Great Giveaway of 52/53 meant that once the General or Conditional was earned, many new hams thought they'd "done it all" and were "set for life".
A typical path was to get the Novice license, work like mad to get on the air, get the code speed to 13 wpm, study various books on the General test, and get the General or Conditional before the Novice year ended. Once that G or C license was in hand, the new ham could relax.....and many did.
FCC had expected that many hams would go on to the Extra "because it was there" - but, according to the 1963 Callbook, there were only 3,164 Extras out of 254,420 amateurs in the 48 CONUS states. That's 1.2% - not enough to satisfy FCC.
Read some more magazines from that time - in particular the QST articles that detail the whys and wherefores. Get the FULL picture.