Debian certainly does not have steeper learning curve, it's just less "shiny" compared to other distros.
By "shiny" I mean for instance Windows 11 is shiny compared to Windows 7 which is not due to shiny UI and shiny software that looks modern and cool.
In that sense Debian is not modern or cool.
Debian is most often used for servers and for people who value stability.
The time when Debian becomes difficult to use and troubleshoot is when you don't do things "Debian's way", to understand what this means I'd have to write a lot here but if you're interested there is documentation that explains the mistery behind it:
wiki.debian.org
You decode for yourself, please don't listen to me, but if I were again to choose a Linux distro it would again be debian, I just love 99% of it. but that's just me.