When upgrading, anaconda removed my old kernel. The new kernel did not boot due to mkinitrd problems (now fixed). This is violating the oft-repeated advice to _NEVER_ 'rpm -U' a kernel package. And it made my system not boot.
An anaconda upgrade always has and always will upgrade kernels. Userspace is regularly depending on features being present in "new enough" kernels and leaving an older kernel causes other strange and unique breakage.