I always found it funny that companies will go to extreme Herculean lengths to hire the best programmers, and are incredibly fearful and paranoid that they could be making a "bad hire", and yet once hired they don't spend a second making sure engineers aren't completely running the software product off the rails and killing the company internally. The author mentions trying to rewrite Etsy's backend in Scala and Mong…
If your engineering team is the one pushing in that direction I'd reckon the company was in a bad spot to begin with to have hired that team because it strongly indicates that the management layer (head of tech/CTO) has no technical clue.
Hire strong Lead Developers with a proven track record of delivering value to companies they worked at and you'll be mostly fine.
Also there's not much to study, in 99% of the cases in a web based startup if your stack deviates from a monolith with one of PHP/Ruby/Python/.NET/Go + Mysql/Postgres/MSSQL you're doing it wrong.