It's been more than a decade since they replaced AFP with SMB as the default protocol for file sharing, and they've been warning that AFP would be going away for years.

I've built a side project to run Samba 4 on the Time Capsule: https://github.com/jamesyc/TimeCapsuleSMB

Yeah but AFP is still performing way better than SMB on Mac for any fast networking. Like 10GigE and faster. Apple SMB stack is a disaster, and thoroughly unprofessional. NFS is faster, too, but unfortunately the Finder, being the rat nest of bugs it is, has often trouble with NFS shares.