I worked as a UX designer and researcher for about a decade starting at around 2007.

First of all, I don't fully recognize TFA's description of what a UX researcher primarily does. It almost sounds like user testing, which shouldn't require a different hat. That's just something you do to evaluate the product. Designers and developers do that anyway (hopefully).

What I did when I put on the "researcher" hat was (I guess, after reading this article) more akin to market research, but within the existing market.

For example, while working with a big holiday/vacation company (operating flights + resorts), we uncovered that a significant portion of the customers staying at their "family friendly" resorts didn't want to be there. They were typically couples who had done fairly adventurous trips when younger, then they'd married, and had kids. They hated the enclosed, catered, walled feeling of these resorts, but thought it'd be the best they could do with a newborn on their hands.

Awareness of this group of people might feel obvious today, but at the time it was a genuine discovery that lead to development of both services and marketing. While you might argue that the company gets their custom anyway, so what does it matter, the fact was that these people left the resort with low ratings, and a low opinion of the company, which they would announce to their peers in $important-demographic on social media and verbally. I.e., long-term damage to brand and customer retention. They freely chose to stay at the resort, and then felt resentment towards the company for it not being a mountain climbing holiday or whatever. It's illogical, but that's what they did.

Secondly, these types of discoveries can't be produced predictably. Either there is something you don't know about your customers or competitors, or there isn't. Initial efforts might yield a lot, but perhaps there is a saturation point along the way, where more research of the same nature at that particular point in time will yield diminishing results? Well, that doesn't matter, because these people have been hired to do research, so they will keep doing it, whether it's useful or not.

I don't understand the separation of design and research into different roles. To me, a designer should be able to go off and do research if it's warranted. Maybe I'm old school, but separating it feels like separating a developer into two people: one whose only job is to find new libraries and read documentation, and one whose only job it is to type into an editor.

Thirdly, to those griping about "UX ruined UI": it did not. UX is what got it to the point you're imagining as "good old days". What damages UX in the long run is shifting incentives (resulting in dark patterns) and a variation of the above, but on the design side: you needed a UX team of a certain size to get to the design you have, but you don't need an engine of that size to maintain it. If your UX department is oversized, I suspect that they will start inventing tasks for themselves and do things that aren't strictly benificial.

This goes for all roles, arguably. More people doesn't equal more productivity, and at some ratio of number of people vs. real problems for them to tackle, the productivity becomes negative.

Also, a UX department as some kind of "other entity" is not a good setup either, in my opinion. In my experience, UX has worked best when it's a cross-disciplinary focus rather than an isolated group of individuals imposing their will and "owning" the UI.

As a UX designer, your most important job is to get people who don't regularly talk to each other into the same room. You don't have to be the cleverest person in the room wrt UI, but you do have to be the person who can bring the user's point of view into a room where other, equally important points of view, are represented. UX can't be effectively done in isolation.