As a compilers enthusiast for more than a decade, it is marvelous how analyzing and manipulating code has become more accessible in recent years and the possibilities it unlocks... very excited to empower teams to make edits for real web apps and save their developers time.
Feel free to contact me as well at: etai[at]flycode.com
Now, Roslyn ins't news anymore :) We have source generators in C#, and we not only have more main stream compiler plugins & annotation processor in Java and Kotlin (that spends a lot of time on their compiler API).
The same process has happened for the JavaScript ecosystem. The AST revolution has hit the frontend/JS ecosystem big-time. Tools like Babel (and derivatives like jscodeshift and recast) have democratized analysis and transformation of code bases. I urge you to play around with ASTExplorer to see how vast is the support for getting a proper AST for source-code.
Another big factor is the maturity GitHub marketplace. Today, smaller teams are able to ship production-ready apps for GitHub as the APIs have stabilized and are much documented than a few years ago.
All these together makes code-editing products much more feasible than a few years ago. It's not that AST and source editing novel ideas did not exist it's just they matured enough that you can actually build a product that targets a big enough segment of the market.