I don't disagree on a permanent basis - but I've done plenty of more temporary stuff where I've been thankful that the system had WiFi built in until a wired connection can be established. Actually going through this right now having just moved house.
I feel that motherboard manufacturers probably go a bit overboard when it comes to onboard sound, not that it's really that bad in a pinch - even just tested the front audio jack on my Lian Li O11 XL connected to my Gigabyte board, and it sounded fine.
But just basic audio, basic networking (i.e., what works with the chipset / southbridge / PCH), and wireless, well, these are just really cheap in the scheme of things, and with PCIe slots becoming rarer for some reason, it definitely makes sense to have these integrated.
WiFi is just weird because the functionality is almost always on a discrete card, usually soldered on for laptops but on desktops, there's a slot used that otherwise has no purpose.
And again, any and all of these functions can be disabled in the BIOS such that the OS doesn't even see them.