Which require that data take a round trip between the R process and the database. It's not uncommon for these jobs to spend more time in the read/write step than doing meaningful work, and why I prefer dbt when possible to keep transformations as close to the data as possible.
Sadly, the company closed this June, and even the website is already down.
ETA: Seems it isn't. https://www.deepchannel.com/ That what you meant?
In that sense it should only be used for last mile data transformations. Not for wrangling raw data into neat tables.
Edit: I am also curious why you consider SQL to be inferior for the latter?
After that step the data is a lot more uniform, so then it's easy to use SQL.
A lot of these discussions are basically "can we please just use the language/tooling we know", and sometimes the answer's yes! A lot of people breathe a big sigh of relief when they discover you can use like, Spark through Python and what-not. Regardless of whether or not it's a good idea or good use of resources, this space is advancing because the market demands it. But like, I don't think you're ever gonna use dbt with not-SQL; it's all in on SQL. Feels like maybe it was the wrong fit for your team.
I should say I'm not sure if your coworker was an SQL person so dunno if this directly applies. Just saying what my experience has been.
I am currently building my analytics pipelines on top of R's dbplyr package, which allows me to run dplyr operations on database tables just as if they were local data frames. Since it's R, it's not without warts, but at least I get to use a real programming language and the free and fantastic RStudio IDE.