So you didn't try the specific build, I infer (I did somewhat skip over your voluminous citations of your doubtless excellent AX record, so sorry if I missed something).
Coincidentally just before I saw your reply I was reading a reddit post: Taking the new ARX chieftain for a spin (to Hadad from someone describing themselves as "far from a great AX pilot":
A couple of comments on the thread that I agreed with:
and
That highly skilled practitioners can solo Hydras in Asp Scouts, while admirable, is largely irrelevant. A pre-build should require moderate skill to achieve results and offer the opportunity to improve.
The facts seem to support the view that extreme skill is not necessary to get a taste of AX activity using the "AX combat jumpstart".
It's perhaps worth recalling that the pre-builds are desribed as "a great springboard for players, both new and existing, to build from and shape as they see fit".
The fact that the build can be improved indicates (to me) an intention to induct the player into AX build concepts (like no shield, low emissions engineering, etc.) rather than a failure to understand basic mechanics by the creators of those mechanics.
The pre-build looks like a compromise not only between providing enough value and providing too much value, but between facilitating the various activities under the AX umbrella. Clearly, the player is expected to specialise it according to what they want to do.
So players will need to gain skill, learn build concepts, and gather and apply resources to be effective with the pre-build.
Playing the game and progression will be required to do this.
This (IMO) is a Good Thing.
yeap, precisely this

The AX jumpstart Chief is far from terrible even tho is not optimal either.
It can allow Scout hunting, Titan visits and maybe even toying with Cyclops - with 0 rebuy - while still keeping things sort of balanced (as in is not OP in the hands of a Pro while being usable even by noobs)