Honestly probably got the project to more maintainable state. Probably didn't need the rewrite to do it in a new lang to do it (the real killer hear it sounds like).
Those monoliths suck on the operations side, and even worse when it's a corpse holding up the foundation to other projects that actually need it to change. Need to scale? good luck that decades old pizza box we call a server isn't supported anymore. Oh of course we can spend millions virtualizing dead hardware to keep it running the same.