if you do this with 4 or 200 machines, does not make a big difference.
Maybe some of that also applies to 4 servers, but to a way lesser extent.
Having to maintain 95% less servers is worth it even if they didn't save any money IMO.
This also could lead to them reducing their engineering team that maintains these services which would reduce costs even more.
It's not esoteric. It's a modern programing language, with 35 years behind its Virtual machine.
1 in 3 phone calls you've ever made was routed through a telephon switch written in a lang implemented in BEAM virtual machine.
WhatsApp was written in a lang implemented on the BEAM.
> I'm willing to bet that way fewer people in the company/industry understand the new codebase and can make changes to it.
It's really not hard to learn. It's not Haskell, It's not Coq, It's not Brainfuck.
You could pick up the syntax and the major semantics in a weekend.
"rewriting in another language reduced the number of servers by 95%" is hard to beat, but at the same time, this saves "only" 2m a year, or about 0.3% of FY22 cost of revenue (per another post)
Pinterest per employee revenue seems to be around 1m, which basically suggest that this could even be a worse than average allocation of resources.
My takeaway would be "don’t bother with this kind of optimisation before you reach a scale where you can afford to do marginal improvements"