A lot of this is myth. At the time that I started with GE in 1964, Alco's share of the loco market was six percent. GE's was 4 percent! When I made an idle comment to my boss that we could stay in business if we could get to 25% market share by targeting Alco, he looked at me with a great deal of annoyance. He told me that our target was EMD, which had 90% of the market. He said specifically "why in h*** would we even bother to target Alco with their "peanuts" for market share?" By 1964, Alco was "dead meat" with a market share that was insignificant, and survived for four more years by licensing their diesel engine to India, Australia, and Canada.
When I had the responsibility for several railroad accounts, each and every one was scrapping locos from all minority builders, and some stored Alcos only to cover traffic peaks until they could buy new power.
Alco diesels had some good design features and the GE main generator and traction motors were well regarded. The real problem was the Alco engine, both the 244 and the 251. (GE has to share some of the blame for the locomotive's control system, which used an amplydine excitation system that no railroad mechanic ever learned to properly adjust. And the GE air cooled turbo was a big problem until we convinced Alco that a water cooled turbo was required to meet the application.)
I remember one stressful meeting with the Wabash Railroad, when the Alco man in attendance told the Wabash mechanical guy that the reason for the poor performance of the railroad's Alcos was that the oil and filters were not changed often enough. The Wabash mechanical guy motioned for ALL of us to follow him outside, and he proceeded to a gondola car and asked the Alco guy to climb the ladder and tell everyone what he saw. The car was filled with Alco oil filters.....
A NYC mechanical guy told me that Alco PA's must always be paired with an EMD E7 or E8, and they must NEVER be out "alone". The railroad made every attempt to keep them between Harmon and Albany, since there was "help" at both ends should they encounter trouble.
It was before my work career, but right after the war Alco had a series of crippling strikes in Schenectady, and those work stoppages did not allow Alco to fully capitalize on the large demand for diesels. Alco was also slow to fully embrace dieselization, understandable in view of the general excellence of their steam designs.
GE ended its partnership with Alco before I started my career. I had heard that with a four percent market share, there were no scale/volume economies that Alco was providing that warranted a discount. Most of the major railroads bought more stuff than Alco did.
GE didn't bury Alco, they buried themselves.
The best engines that Alco ever made had wheel arrangements, like 4-6-4, 4-8-4, 4-6-6-4, 4-8-8-4, etc.