Question Multi vs Single-Rail Power Supplies - Why the switch?

The usual answer for such decisions is economics or marketing.
I thought there would be more science to the issue; but it seems you are probably right. According this this article (linked below), a lot of PSU makers were messing up on multiple +12V rails and it was causing issues, plus it's cheaper and requires less engineering to produce a single +12V rail. The multiple +12V rails were mainly a marketing ploy and was being abused by inferior manufacturers, so a single effective +12V rail became the norm again.
Just a few years ago, most gaming and high-end PSUs were using multiple +12V rails to add that extra layer of OCP protection.

Why did PSU makers go back to making single-rail units?

PS: I just read this post:
The whole dual rail advertising was prevalent at times when hardware was built with only speed in mind and no power concerns (around 2005).
Intel required the +12V rail split, since many PSU were cheaply made.
It was also a sale point to advertise multiple rails on a PSU, since people saw PSUs with that feature as reliable.

That has changed lately and components are build with power consumption in mind not just speed, so no one is advertising it.
Intel not longer requires the +12V rail split.

When buying a PSU go for reliability.

By the way, Corsair Link software allows you to switch between single and multirail on compatible PSUs
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