Did several domain experts tell you this or are you making it up?
> I can't imagine how anyone, in any field of information systems, is not multiples more effective than they were five years ago.
Perhaps "they are massively more complex than anything I've done"
It's an assertion among eight other engineers on the project with ~15 years of experience in the domain. They are domain experts. This part isn't up for debate.
Just so I'm clear then, because this adds a lot of context: Nobody else worked on the 2 softwares you mentioned, but you are on a team? Are the softwares part of a business, one that's making money?
Correct, they didn't directly work on these features. These integrate into a larger pieces of software, both of which directly generate revenue from these features.
Were these larger pieces of software _already_ generating revenue, before your features?
First dollar is the hardest one to make.