It’s more of an evolved cobbled together mess than RPM has ever been. Things got accreted on top of tarballs by necessity.
I have both hated and appreciated debian packaging, largely depending on the thing I was trying to package at the time. Things implemented in C/C++ and built with vanilla cmake are feasible. Other things get complicated very quickly.
If you're willing to absorb that complication, then debhelper really will handle any and every situation. It is a hell of an investment, though.
In the distant past I did a small amount of packaging both formats. We're talking 10-20 years ago (the past decade I'm only deb packages, but I "cheat" as described elsewhere, using "dpkg-deb"). I wouldn't say "deb" is inferior, but I would say it's much harder. I actively enjoyed creating SRPMs, but never got past loathing building deb srcs. I've had friends who loved debs, or at least could create them in their sleep, but I never got anywhere near there.