Time "Machine" on MacOS continues to work (though it's clearly not as important to Apple as it once was).
The issue is: if you want to back up a phone: it will take space from your laptop and it must be tethered to do the backup. This means that if you have a 1TiB phone, like I do, you need at least 1TiB of local disk on your laptop to be able to do a single backup if the phone is anywhere near full.
This is in contrast to how Time Capsule works right now for MacOS, whereby you have an SMB share (like, a 100+TiB NAS) and your laptop will just back itself up when it can.
Such a feature would be pretty killer on iPhones/iPads, or having a "photo server" to offload your photos... idk, but Apple won't do it.
That said, we're very much in "power user" territory now, and it does nothing to support the untethered use-case that Time Machine allows.
In fact, the real punch of my comment before was that this would be a way of selling additional hardware (the old time-capsules) to consumers.