I tried hibernation on Thinkpad X1 Carbon Gen 1, Gen 5, Gen 7, and Gen 11. They all work. As per https://chaos.social/@waldi/110683468203241035 , I believe that the definition of "modern system" Waldi refers to means catering to a Windows world, something not deeply relevant to the Debian use case.
Steve's point about servers with more RAM than local storage caters a nice use case to the detriment of the default. It does not design for the common case with significantly more local storage than RAM, and certainly violates the principle of least surprise. Server operators are also more likely to have automation, change control, Q&A processes, custom install options, hardware, etc. than normal users. In other words: They are more likely to diverge from the default settings. Desktop users likely do not care, or notice, either way. Using only part of the local storage and reserving more with LVM is certainly not the default use case, either. It is also not the default behavior of the guided installation. As such, the current behavior is a breaking change for laptop users and leaves them with a broken system; when they realize why hibernation does not work they need to reinstall the system or reformat by hand with all the data moving that entails. The fact that we're stuck with this for a whole stable release cycle makes things even worse. Richard