Do you mean figuratively that OP is replacing Cobol? Because I don't see that in the article. It mentions other technology that I would not associate with a super-conservative stack - like Databricks, JSON, Postgres and Google Analytics. So I'm a bit confused by your comment. And by all the downvotes, honestly.
I just pointed out that personally I would not consider Lambda - which has been a stable and popular technology for 10 years - to be cutting-edge. It's not old but also not cutting-edge imo. I would reserve that term to newer technology. Apparently a controversial view on HN, which is interesting.
To respond to your question, I did work for a bank in 2017 with moving certain burst-type processing to a set of Lambdas.
I worked for a company that went all in on Lambda as well. The knots they had to twist themselves into so that everything ran nice and smooth in Lambda environment was mindboggling. We have certain actions like orders that would pass through 8 Lambdas before completion because of execution time or just the big code base would result in 7 seconds start up time (node) so it would get broken down. If any of them failed, and it felt like failed a ton due to Amazon backend stuff, it was a nightmare to resolve.
All of it could probably been handled by larger node application in docker container somewhere but AUTO SCALING, FAILOVER, SERVERLESS!
Once I started as SRE for a new team, we built a larger monolith using Node and docker on EC2. We would get massive complements for our uptime and reliability but there were some architects extremely unhappy when I revealed in division presentation that it was just Docker + m4.xlarge running Ubuntu 18.04. When I left, more and more Lambdas were being broken down into docker running on EC2. They are probably on some container managed solution now.
