...you can't be serious? Every other company that has been writing code for 20+ years probably has code that is 20+ years old. Just look at banks.
It's an incorrect impression, obviously.
For >20 year old code, Calc.exe is just one example off the top of my head - https://github.com/Microsoft/calculator
The majority of the products I've personally worked on over my 15 year career in software development are still doing useful things and contain code written more than 20 years ago.
Banks are probably one of the few examples of very old COBOL code that's still running (although they've been trying to get rid of it for years), which is the exception that proves the rule. Regardless, if you approached bank executives and said, "we've compromised all of your systems and we're going to delete either all of your code or all of your data, you pick", which one do you seriously think they're going to pick?
I myself am still maintaining a large system that I started about 20 years ago, and maybe only a couple of functions from that time have survived to this day, but all of that data is still there and valuable.
Though I'd say that a big reason for that is because very few companies even had a backend 20 years ago compared to today. The ones which did are likely not really consumer oriented, but if you ask medical companies (EMRs), governments, and insurance companies, I'm sure it's not too uncommon to use applications which have codebases that are from before 2002.
Also, 10-20 years from now, I'm sure it will be quite common for companies to have backend services code which are 20 years old. There are still a lot of companies having Java 7 and earlier in production, and that's 11+ years now.
But I agree with what you're saying, it's much easier to get rid of code vs. data, and data is also a lot more valuable!
Additionally, psychometric tests such as the GRE and SAT have been around for a long time and process lots and lots of data (especially relative to when they were first scaled out).
My former company makes B2B software that's entire purpose is to process business data and our codebase started in 1999 and plenty of original code is still in there. Entire modules have barely been updated, those modules are working and the business needs haven't changed.
Speaking of old business software, PeopleSoft is ubiquitous at big companies and has been around forever. Their codebase probably has code two decades old. The frontend looks like it hasn't been updated in the last decade.