ECM controlling the alternator's field has become a 'standard' engineering practice, and I won't say it's a 'good' thing...

There's several things they're doing here... FIRST... is that they're increasing idle speed along with field current to push system voltage up when it's low (at idle).

Next thing they're doing, is shedding mechanical load (from engine accessories) to provide more horsepower at the wheels, when you request it.  On WFO they disengage the AC compressor and the alternator field... and while it doesn't seem like much, at the high end of the RPM band, the 15 ft-lbs or so constitutes 15hp or so that could be pushing the wheels... they let the AC pressure drop, and the battery carry the electrical loads for a few moments, and call it 'good'.

As far as all the rest of the goofy antics, a whole lot of wire and connector rot happens, and it doesn't take but a little, particularly in a ground strap, before things act crazy.  With electrical interlock switches everywhere, vehicles do this.

A friend of mine who is an engineer in the industry confirmed my suspicion about this- the inclusion of all this complexity helps accurately determine the point in service life which a consumer goes looking for a new vehicle.  The most powerful competetor to new vehicle sales, is USED VEHICLES... and used vehicle prices are the one thing that severely limits new vehicle prices.  If a consumer is tired of dealing with problems, their propensity to choose a secondhand vehicle will sour, which means they buy (and finance) something new.

Most will identify it as 'planned obsolescence', but it's certainly not a matter of being obsolete, it's simply a matter of making some point intentionally degradable in such a way that the vehicle's service life value drops off rapidly at some point which doesn't result in a safety recall or warranty storm.

Realize, it's a psychological war of attrition, and the companies that do this, are very, very careful to obfuscate HOW they do it.  One of the eariest tools is the "CHECK ENGINE LIGHT".  It was originally introduced because of limited display and processing capacity, but manufacturers found that it was a useful 'tool' for several things... like... having people bring in cars for unnecessary 'scheduled maintainance' visits.  They also used it as a tool to meet certain emmissions requirements (that manufacturers identified as resolvable by 'scheduled maintenance').  As time went on, manufacturers found that by making the CEL light come on for any possible reason (like aging ground wires) that owners would be more willing to simply buy a new car, and 'let the next person deal with it'.

Another GREAT write up Dave ! Confirms  what I've thought for decades and why 'old; stuff is better than new.Dave does explain WHY so many things, like appliances, are 'use once, buy another'.

Wonder if some smart guy will market a 'kit' of a 1 wire alternator and a 'fudge' connector to FIX, once and for all , the 'bad $1,000 alternators' we see today ?

While I've spent 1/2 my life programming  microcomputers' I see NO good reason to have the ECU control the alternator.it's just 'bad'.

  If I were to drive a new vehicle off the lot and then it wouldn't start the next day, it would remain at the dealer after getting towed there, sounds like a LEMON right from the start.

 MY mechanical diesels will get me home if nothing whatsoever in the electrical system is working. I've had to do that a couple of times, but they always get me home.