Having actually partially designed and maintained a visual programming product with I guess what would be called a time travel debugger (among many other fascinating and strange features) inside of a major technology company, the biggest push back was always from developers themselves. These things sound good, and often they're very useful to those without strong programming backgrounds, but inevitably developers are pretty aggressive about poo-pooing tools like this as lots of things are much harder to implement, like diffing for example. The tool itself was honestly very radical (we were able to do a ton of really cutting edge things around resource scheduling, containerization pre-Docker, real actual shared time travel debugging at massive scale), but in the end, I think the company shitcanned it for something much simpler.
