I think you should describe what counts as a theoretical breakthrough to you. The rest of us seem to think that writing some flowcharts or nearly English code in 10 minutes with a verified application coming out is a mix of great advances in theory and tooling over the years. Sure didn't do that in the COBOL days.

Another example is the K framework where they just use rewrite rules in a decidable logic with some supported tooling. That specific theory, their logical strategy, let them do a whole semantics for C with undefined behavior included in just a few thousands lines of specs. In form of KCC, it can also be used as a compiler.

The oldest one, from co-inventor of software engineering, let you specify functional, structural, and resource requirements in a logical notation with the tool synthesizing about everything else for you. That was 001 Tool Suite. The thing is, I can only imagine tools getting much better than that because any development will require human brains turning problem descriptions, constraints, etc into precise statements. Which is what specs are. That we're already at spec-to-code synthesis and proof for some of these tools seems like something that can't be hand-waived away as "no theoretical breakthrough there just lots of new tools."