I'm saying that being designed around the singular task of word processing would have made it a platform/ecosystem failure, even if was a nominally successful one-off product.
The Macintosh (specifically the original 128k version) was a dismal market failure too. What succeeded (relatively speaking) was the platform/ecosystem.
Even the 128k was reasonably successful commercially. Hundreds of thousands of units sold, which was quite good for the time. Inflation-adjusted, it cost quite a bit more than the Vision Pro. They sold the same model with very minor revisions (512, then 512e) into mid-1987.
The 1986 Macintosh Plus was a huge market success and it is only modestly different from the original. Even the SE and Classic didn't change things much.
I agree with you about the Plus/SE, but the very existence of these products was a direct result of it being a successful ecosystem. As you correctly point out, the 128k/512k sold impressively well considering its high price. This was possible because it was an ambitious product, which Raskintosh was not.
Let's be clear, Raskintosh isn't the Macintosh that history eventually proved successful. What Raskin wanted was a significantly simpler and cheaper machine, more squarely pitted against offerings from Amstrad, Atari, and Commodore. Not to mention Apple's own array of ecosystem failures, such as Apple III, Lisa, IIGS, or indeed Newton.
Based on the raw odds, plus hindsight, I contend it would have been an ecosystem failure even if it saw some sales success. By not reaching for the stars, it would have been yet another in a long line of quirky mid-eighties, commercially successful, but short-lived platforms.
The Macintosh (specifically the original 128k version) was a dismal market failure too. What succeeded (relatively speaking) was the platform/ecosystem.