Agile developers expect agile everything. Ubuntu happens to just be a happy compromise between agile and waterfall.
If you look at RHEL, it's 5-10 year old packages, kept alive by an enormous engineering team that backports fixes to old, dead software, which creates a huge pile of technical debt for any developer trying to use "modern", highly modular frameworks.
As far as developers go, In the Ruby, Python, and Node ecosystems, anything that's not the latest doesn't exist. They don't use the system package management, they use gem, pip, and npm. They really don't care about the underlying OS, until it gets in the way, and getting in the way is exactly what a decade-old OS does.
Just to throw out an example. Take some modern ruby on rails application, say Discourse. (discourse.org). Go download a tarball from github. Now try to make it work with nothing but software from the official RHEL repository. Let me know how that works out for you. After you tear out all your hair and skin trying to do that, try to get the pieces from 3rd party repos that will make that work. See how much you have to bring in as far as new libraries and new packages just to make it work. It's still a nightmare even with the 3rd party repos, and that RHEL support contract doesn't cover them - every single piece that's likely to break your application, is now outside of your support agreement, so your company is now wasting at least $799/year for support.
Here you go, seems straightforward and easy enough: https://meta.discourse.org/t/i...
If modern, highly modern frameworks are interested in getting into the big enterprise space, then they will dedicate the time to making their software work with RHEL. If a company is running Ubuntu in production, then they don't particularly care that much about stability, have a small server install base, or a team that can hack around enough to make things work.