Rainer,
the handbook still recommends to build sound modules (and many many others) as
module, because it is easier than doing a static configuration. Now, you can
ask, why someone wants to build it static into the kernel. The answer is:
Security !
Maybe you know this wiki article:
https://wiki.gentoo.org/wiki/Signed_kernel_module_support
This is a pre-condition for enabling LOCKDOWN in the kernel ... OR ... you
have NO modules support (=monolithic kernel) ! So, you have the choice which
way you want to go.
I am using a monolithic kernel also. Dont try to enable lockdown in your
kernel if you use unsigned modules. ;-) I wrote a big warning in my wiki
article:
https://wiki.gentoo.org/wiki/User:Pietinger/Tutorials/
Kernel_Hardening_with_KSPP
Regards,
Peter